Mop Clamp for String Mops Wet Mop Handle Gripper Clamp Style. This Mop clamp converts your standard Microfiber Mop Handle to a string mop design. all you do is screw it on the bottom of your mop handle and attach our string mop heads. This is an amazing device for the price. It compares to the Rubbermaid Brute Clamp Style Wet String Mop Handle.