Customer Reviews: WHOOP SuperKnit Accessory Band 4.0 Heather 959 02 006 WHOOP Ultra Soft SuperKnit Accessory Wristband 4.0 For Enhanced WHOOP Ultra Soft SuperKnit Accessory Wristband 4.0 For Enhanced WHOOP Ultra Soft SuperKnit Accessory Wristband 4.0 For Enhanced Amazon.com: WHOOP Ultra Soft SuperKnit Accessory Wristband 4.0 for Whoop 4.0 Experience Enhanced with SuperKnit Wristband. When it comes to any performance or profession, nothing should stand in the way of unlocking your potential. Its why we designed our premium SuperKnit band that improves upon our best selling ProKnit material. Engineered with an ultra soft backing for enhanced comfort and durability, so you can stay in the zone with zero distractions. Includes Band, Hook, Clasp, and Fast Link slider that makes swapping bands easier than ever. Only compatible with WHOOP 4. 0.