Babolat POP WRIST SENSOR The Babolat POP now gives players the ability to start tracking their game with any racquet they use. The first tennis-specific wearable device, POP measures users swing speed, spin and style, the style is measured as how smooth and fluid your stroke is... Size - (See Description) | Color - (See Description) Authorized Babolat Dealer. All racquets are strung and ready for the courts! SEE SELLER DETAILS FOR RETURN POLICY.