OTC's Professional Mechanics Collet is designed to securely grasp broken studs with as little as 1/4 inch exposed, including corroded or frozen exhaust manifold studs Compact design lets this versatile tool get into tough to reach spots for extraction -in an around suspension and steering components, tight exhaust manifold clearances and more Designed to draw tight - within 1/16 inch of head surface to ensure a secure and stable attachment that greatly reduces tipping Kit includes 4 collets (6mm, 7mm, 8mm, 10mm) sized to fit common applications including exhaust manifold studs, broken head bolts, and other engine and chassis fasteners Durable blow-molded storage case keeps tools contained and organized so they are ready when you need them