Strain Relief system for power cords. 3/8" Mip Connection. For cord size 16-3, 18-3 Water tight connection as you tighten the top spring it squeezes down on the power cord The 3/8 Fip retaining ring is not included. See Example below on equipment below Clean Storm SBMWAX49 Breaker Buster Breaker Separate Circuit Indicator Locator in Water Resistant Box Current or past OEM Associations: Mytee H856, EDIC B11199 Karcher 8.663-336.0