These strap buttons are very light weight and are not intended for tube guitar heads or anything over 30 pounds. They don't come with bolts or nuts but they have an overall strap size that's so disappointing. Although they look like amp or speaker knobs in the picture, they are smaller and lighter than any strap knob on any of my amps or speakers. They turned out to be VERY small and light for my application, I would never trust them. There is a metal strap inside the handle which gives it strength but the strap is flimsy and with a lot of weight the ends just pull out, I've had this before and it's a real shame when it does that during loading. at 2 o'clock in the rain. I will not buy these again.