41 pc Metric Tap and Hex Die Set ORS NASCO Twist lock system ensures secure closure Spring loaded Twist lock system ensures secure closure Spring loaded keeper simplifies use Rust resistant zinc dichromate plating High voltage insulating tape that provides excellent thermal dissipation of splice heat Provides immediate moisture seal and void free buildups Rated up to 194° F (90° C) continuous operating temperatures and short term 266° F (130° C) overload service Designed to ensure that bolts fit tightly and anchor securely Plug taps have 3 to 5 chamfered threads and are for general purpose applications Hex head shape is designed for use in die stock and adjustable wrenches