YOYA EMT Conduit Locknut 1.zinc casting 2.1/2"-- 4" 3.for rigid/IMC fitting YOYA EMT Conduit Locknut1.size: 1/2", 3/4", 1", 1-1/4", 1-1/2", 2", 2-1/2", 3", 3-1/2", 4"2.material: Zinc Die Casting,steel3.Indoor or outdoor applications. Use to secure Rigid conduit I.M.C. conduit or various threaded fittings to a steel outlet box or other metal enclosure.