Review on Vacuum Suction Cup Camera Mount With Hand Pump And Threaded Base - Ideal For Glass And Car Surfaces by Scott Richardson

This review is for the 6" cup version. There are some major design issues with this version. The hole size is 5/16"-18, which would be nice and sturdy at the rated weight of roughly 110lbs, but you can only get a 5/16 bolt 2-3 threads deep (less than 1/4") into the hole. The hole rests directly above the plastic housing of the suction pump, so over tightening will result in a cracked pump housing. The hole threading stops well short of the pump housing, probably to prevent the above mentioned cracked pump housing. The rest of the unit itself is nice and sturdy, unfortunately the point of connection is poorly thought out.I haven't decided if I want to risk using it with some loctite. An answered question above suggested that the actual thread was metric. I tried an M8 hand tight into the hole, but still didn't get more than 2-3 threads in before binding.