Outstanding USA racing quality!  Direct fit for stock U20 retainers or our USA production Chromoly retainers.   Highly recommended for extreme performance U-20's!  
 
Also 100% suitable for street application depending on the seat pressure and cam you select.   Can be used with OEM stem seals and seats or aftermarket seals.
 
Far better quality than cheap springs offered by the discount vendor!  Money back if you don't agree!