Tough plastic case with a slide action blade lock. Locking spring assisted blade return. Rivetted metal end hook. Steel belt clip & wrist strap. Action lock holds the blade precisely where you want it. Blades and hooks are heavy gauge and corrosion resistant. Self-aligning hooks ensure accuracy for internal and external measurements. 5m and longer tape hooks have 4 rivets (3M/10' tape hooks have 2).