This is the Replacement Air Filter Element for the Tower Hobbies Nitro ST-15 Truck. FEATURES: White foam construction INCLUDES: One air filter element (Key# 41) REQUIRES: Air Filter Housing (TOWC6030) (Key# 40) Air filter oil, use DTXC2465. SPECS: Height: 23mm Diameter: 24mm tjt 2/1/01 ir/jl