Continuous-thread studs are threaded from end to end and are often used for flange bolting with two nuts applied. Tap-end studs have a short thread on one end, called the tap end. Double-end studs have equal-length threads on each end to accommodate a nut. Type : Type A :- Recommended for use in steel. Type B :- Recommended for use in Cast Iron. Type C :- Recommended for use in Aluminum Alloys.