Product Description Specifications Precision machined from 6AL4V titanium, these retainers feature better material consistency and bullet proof durability. These 10 degree retainers fit engines with 1.625" OD valve springs such as our 996, 998, 26099 and 991 springs. Category: Engine Components>Valve Springs, Retainers Core: N LTL: N MPN: 733-16 Proposition 65: Y Special Order: Y