Material: high strength steel can withstand unusual physical forces. The size of padlocks limits the number of keys that can change, so we recommend that these padlocks be used in smaller factories that require no more than 1400 key passwords. Cadmium plating provides corrosion resistance. Safety padlocks are distinguished by the use of different colored plastic covers. The temperature range tested is from -20 f to +160 f. It is the heaviest security padlock, so if you need to carry more padlocks, you may want to replace them with lighter locks or aluminum locks. There are 8 different colors of plastic sleeve available.