Bumbleride Indie Twin Non PVC Rain Cover Training Aid Type_Junior Tennis Nets Gamma Professional 17 tennis string Gamma Professional 17 tennis string provides over 20% greater dynamic resiliency and dynamic elasticity compared to other multifilament synthetic strings Our sock like upper and injection molded support cage are designed to promote the healthy development of feet and the lower extremities by supporting the weight bearing structure of their developing foot while uniquely stabilizing their still forming heel this non PVC rain cover protects against the elements Compatible with all Indie Twin models from 2018 or later