QA1 9029-164 Shock Extension Aluminum 2in. Long 9/16in.-18 ThreadQA1 9029 164 Shock Extension Aluminum 2in. Long 9 16in. 18 Thread QA1's Aluminum Shock Extensions can give you a little more length if needed for your application. With 1 or 2 inch lengths and 9 16 or 1 2 inch thread sizes, you are sure to find one that will fit your needs. Part #9029 164 for all Circle Track shocks except 70 and 82 Series.