These springs were originally used on the 1996 Corvette LT4 engine. Also used on all 1999- Current ZZ4,Fast Burn 385 engines, Fast burn heads, Lt4 heads, and are included with the LT4 hot cam kits.Outer diameter of 1.34" , 101 Lbs pressure @ installed height of 1.78", solid height 1.22" Spring pressure with valve open is 332 lbs. made of high quality silicon ovoid wire. Color coded green. Set of 16. For a single replacement spring use part # 12551483
.The matching retainers for this spring are part # 19171528
, and the keepers are part # 12495503
. Good for up to .530" lift.