This restraint can fit all 6-71 thru 18-71 roots blowers with the 12.25" top opening but the good news is there is also a set of holes that are 15.250" on center so you can use the restraint with a 13.250" on bolt center injector on a large opening roots blower. Bolt centers are 13.250" and opening in the restraint are 12.250" x 4.00".
Specify engine brand, blower size and blower manifold brand when ordering as well as supercharger brand.
Common strap lengths can be chosen from the drop down menu. This is a guideline and the racer should check measurements before ordering: SBC 15.00", BBC 18.00", Fuel Head Hemi 21.00", Fat Head Hemi 24.00" but remember custom strap length can be ordered at time of placing order but customer must specify what length they are after.