one of my favorite poly
"one of my favorite poly strings but not so harsh on the arm."
Tecnifibre
BLACKCODE17:SET
Tecnifibre Black Code 17(1.24mm) provides more spin with slightly less durability than the 16 gauge version. Utilizing a co-polyester core, this string possesses excellent durability with greatly enhanced tension maintenance and feel. Black Code 17 features a pentagonal profile, helpful for generating more spin as the string bites into the ball better. The string uses Tecnifibre's exclusive ThermoCore technology which serves two primary purposes. String-to-string friction is greatly reduced, enhancing durability and further promoting spin and ease of stringing. The ThermoCore technology also gives the string greater flexibility for more power and a softer feel. An excellent choice from all areas of the court with enhanced spin, good power, and a softer feel.
Construction: Extruded polyester monofilament
Color: Black
Gauge: 1.24 mm (17g)
Length: 12.2 m (40 ft)
For more information on strings, see our following blog posts:
Tecnifibre €™s new Polyester String: The Ice Code Cometh
10 Best Soft Co-Poly Strings to Try
Need help selecting a string? Check out our Choosing The Right Tennis String guide for more assistance.
Any original shipping fees are none refundable.

| From | To | Standard Ground* | 2Day | Next Day | |
|---|---|---|---|---|---|
| $0.00 | $49.99 | = | $5.95 | $15.95 | $29.95 |
| $50.00 | $149.99 | = | Free | $15.95 | $34.95 |
| $150.00 | $199.99 | = | Free | $19.95 | $39.95 |
| $200.00 | $9,999.99 | = | Free | $19.95 | $39.95 |
| From | To | USPS Priority* | |
|---|---|---|---|
| $0.00 | $99.99 | = | $19.95 |
| $100.00 | $199.99 | = | $39.95 |
| $200.00 | $9,999.99 | = | $49.95 |
Orders being shipped outside of the Contiguous US or APO addresses will ship by means of the United States Postal Service (USPS) and in some cases FedEx.
**Shipping via USPS Priority provides minimal tracking information and normally delivers within 5-7 business days.
*** Any shipping promotions offered by Tennis Express DOES NOT apply to shipments outside of the contiguous 48 states.
**** Excludes tennis balls, court equipment, stringing machines, ball machines and all oversized items.
At this time, Tennis Express only ships to the United States and all US Territories including Puerto Rico, US Virgin Islands, Guam and military bases. Due to manufacturer restrictions, we are unable to ship to countries outside of the United States.
Return Policy
Tennis Express believes in providing our customers with the best selection of tennis products and innovative game improvement gear. If the products are not to your liking, please take comfort in knowing you can return or exchange unused products within 30 days of the delivery date. Used or worn product is ineligible for a Refund. However, Tennis Express may issue a partial store credit for product returned in a used or worn condition. Credit is at the discretion of Tennis Express based on the amount of wear and use on the product. Store credits expire after 90 days.
How to Return
Submit a return request by visiting Return Portal.
1. Log in with your order number and email.
2. If your order has more than one item, select the items that you want to return.
3. Select the item condition and reason for return. Optionally add any comments.
4. Save and continue to return options.
Once your return request is approved, you'll receive an email with a label or QR code for your FedEx return label and shipping instructions. After the product is returned, you receive a refund.
To qualify for a FREE prepaid FedEx Ground return label:
* Your order must be over $50 (before tax and any shipping fees).
* After your return, the value of what you keep must still be over $50 (before tax and any shipping fees).
* Limit 1 free return label per order.
* Valid only for the continental United States.
Example: You place a $75 order and return a $30 item. Your remaining total is $45, which is under $50, so this order does NOT qualify for free return shipping.
If your order does not qualify for free return shipping, you can still use our return portal for a flat $6.95 fee, which will be deducted from your refund. Otherwise, you're responsible for shipping items back to us, so please hold onto your tracking information.
Please note:
* If you use one of our prepaid labels, you may drop the shipment off at any authorized FedEx or USPS Service Station.
* Refunds will be processed within 3-5 business days from the day we receive the return.
* Any original shipping fees are non-refundable.
* Any store credit issued will expire within 90 days.
QUESTIONS: If you have any questions about our return process, please contact us before shipping back your return: [email protected]
Apparel Returns and Exchanges
* Apparel must be unworn, unwashed, and unused with original tags attached.
* For safety concerns, we cannot accept used or washed clothing.
* Accessories must be unworn, unwashed, and unused with original tags attached.
* Apparel items carry NO warranty from the manufacturer.
Shoe Returns and Exchanges
* Shoes must be in NEW and unworn condition with original product packaging.
* DO NOT use the original shoe box as the outer shipping box. This will ruin the product.
* Accessories must be unworn, unwashed, and unused with original tags attached.
* For shoe outsole warranty claims, please visit our Shoe Warranty page.
Final Sale Notice: All Clearance Shoes and Apparel are Final Sale and not eligible for returns or exchanges.
Racquet and Paddle Returns and Exchanges
* Racquets or Paddles must be in NEW and unused condition with original plastic covering the handle intact.
* Make sure any racquets or paddles are protected to safely endure shipment.
* For racquets strung at Tennis Express, the cost of the string will not be refunded.
* All sales are final on the purchase of used racquets.
* For racquet warranty claims, please visit our Racquet Warranty webpage.
Drop Ship Returns
* Items shipped directly from the manufacturer must be returned to the manufacturer within 30 days of the original delivery date.
* You must request a Return Authorization (RA) from Tennis Express prior to shipping. Please email [email protected] with your return request.
* Drop shipped items must be in new and unused condition with original product packaging.
* Any restocking fees or return shipping costs will be paid for by the customer.
Damages and Issues
Please inspect your order upon reception and contact us immediately if the item is defective or damaged, or if you receive the wrong item, so that we can evaluate the issue and make it right.
Unfortunately, we cannot accept returns on gift cards.
Last Updated 05/07/26
Overall rating: 4.714286 / 5 from 21 reviews.
Review topics: ["feel","durability","string","spin","products","gut","brands","balls","hit","poly"].
"one of my favorite poly strings but not so harsh on the arm."
"Great products and brands, but mobile site can be too aggressive, sale offers, chat icon popping out reduces the motivation to purchase or continue shopping. I had an issue when trying to place the order. Going to the cart, 3 second later it was sending me to the page with sales offers and discounts. It didn’t let me process my purchase. I reached out to the support in the chat and they told me they cannot fix it. 30min or so after the webpage let me do the purchase. Hope this helps to improve the UX and not being too aggressive with the marketing. Oh, btw I got a discount code (copied) but then lost it during this so many issues and back and forth. 😖."
"Good string. Solid durability."
"I really like these strings. I have been using them in a hybrid lately in the mains. Get good spin and they are durable."
"Fast shipping."
"I am enjoying playing with this string. I use it in a hybrid. The durability has been great for me and I they do not give me arm or shoulder problems. I string in the lower 50s. Great string."
"I have used the Prince strings for 30 years with great results. A pro was watching my game and suggested the two new set of strings I ordered. Completely different from what I was using. Didnt think I could play better at this age, but the strings allowed for more topspin and more control. I love it. Sandy Arico"
"Like this string a lot. Huge amount of spin, but easier on the arm than other similar strings. Lacks some power, but that seems to be the trade-off. Durability and tension maintenance has been very good."
"Have been using for a couple years now and love the spin they generate."
"This might just be the best string! Ive used the Solinco and Signum Pro, both are good but I find Im much more consistent with the Black Code and the amount of spin put on the ball is CRAZY, especially my slice shots. I dont know if Ill find a better string."