This is an aftermarket steering wheel hub boss adapter kit for 89-98 Nissan 240SX (Does not work with Hicas [High Capacity Actively Controlled Steering] ). This kit is made of high quality light weight aluminum with rubber, and it is 67.6 mm/2.66 in in thickness with approximate 3.5" in diameter. This hub boss kit comes with 6 holes pattern that is compatible with most aftermarket racing steering wheels (such as Momo, Nardi, etc) and ball bearing type quick release kit, and it is a necessary part if you want to install the aftermarket racing steering wheel. The package comes with 1 x hub boss kit, 6 screws and 1 wrench for installation. Instruction is not included with this package, professional installation is highly recommended.