Lfhelper Universal Roof Hook Ladder Kit, 500 lbs Steel Ladder Stabiliser Ladder Roof Hook with Wheels, Rubber Grip T-Bar for Damage Prevention, Roof Ridge Extension

Poorly designed. The connecting fittings wingnut is too small and bolt is not the type that slots into the square hole to lock so you have to fiddle around to tighten. Not possible to tighten effectively, so each hook slips around. Works with bungy cords to attach to each side of ladder, but a simple retaining bar across the centre would have resolved this.