TECNIFIBRE NRG18NA:SET NRG2 18g Tennis Strings Natual Tecnifibre NRG2 18 (1. 18mm) allows players to generate the most spin and power of the NRG2 family of strings... Size - (See Description) | Color - (Natural) Authorized Tecnifibre Dealer. All racquets are strung and ready for the courts! SEE SELLER DETAILS FOR RETURN POLICY.