The purpose of this coupling is to connect a second length of hose to standard hose that came with my Shop Vac. However, despite purchasing this Shop-Vac coupler and a Shop-Vac hose extension of the proper diameter, this coupling does not provide sufficient grip to keep the two hoses connected. I had to put a layer of duct tape on the cuff of each hose before inserting them into this coupler, then duct tape them together on the outside of the hose and coupler in order to prevent the hoses from slipping out and apart at the slightest nudge. If I'd known I was going to need to use duct tape to hold the hoses together with this coupler I would've simply doubled up on duct tape and done without it.