They are called sheet grips and some "bashers" prefer them to Clecos.Thin metal can have a pinch; bunch up a bit. Thick may not seat. It happens especially on long lines where the sheet can move a bit. Clecos don’t fill the holes perfect. What ever you call the screw in clecos, are nice to help lock in spots. About a gallon and a half of clecos will do a RV nicely.