This is the Wheel Foam for use on the / Futaba 4PK 4-Channel 2.4GHz Transmitter (FUTK4900). / / FEATURES: Foam construction / Black in color / / INCLUDES: One Wheel Foam / / REQUIRES: Installation on the transmitter wheel / / SPECS: Outer Diameter: 48mm (1.9") / Inner Diameter: 38.5mm (1.5") / Width: 18.5mm (0.73")