A lab coat is a cloak specific to SLASH'EM. It provides acid resistance^[1], poison resistance and magic cancellation 3. It replaces the alchemy smock from vanilla nethack, providing the same intrinsics but better magic cancellation. For a character who does not fear drowning attacks, it is worth considering as part of an ascension kit, as SLASH'EM's late game contains some very powerful acidic monsters, which the coat renders considerably less dangerous.

1. ↑ SLASH'EM 0.0.7E7F2/do_wear.c#line206