I learned a good one for those threaded holes visible on your rear fender when using a solo seat. HD license plate bolts fit the thread nicely. 4 bolts in a kit, so use 2 in your plate and 1 or 2 in your fender. Or, share with a friend. I wouldn't recommend any of them to hold a seat down. Just the empty holes. For bolt heads that have a definite "up". They may not tighten perfectly upright. Use a little blue threadlocker (loctite) and tighten by hand until straight.