AP Racing by Essex 2-piece Spline Drive Competition J Hook Disc Pair (380mm)- Porsche 911 991 GT3 CupAP Racing by Essex 2 piece Spline Drive Competition J Hook front disc pair for Porsche 911 (991) GT3 Cup: 380mm front and rear Innovative Spline Drive disc system derived from professional racing applications Designed for: club racing, time trial, autocross, HPDE Works with OE calipers, no modifications required Ultralight 2 piece fully floating AP Racing J Hook disc with anodized billet aluminum hat