I figured a follow up post was in order so here it is. Unless you plan on using most of the strap off of the spool, I wouldn't recommend these. On the maiden rv voyage, I had some truck issues, so i forgot to do a safety check half way to the camp ground. When i went to unload the ranger, all of the straps were loose (4) and the muffler had worn a hole in the rear ramp....all the way through the plywood, about 3 inches in diameter, from moving all around. I had it tied down to the e-tracks, which left most of the strap on the spools, so after a bit of bouncing, it just kept twisting on the spool taking out slack.
On the way home, I used the same 4 automatic ones, with 4 regular ones for a total of 8 and the auto ones were loose again half way home.
I'll find another use for them, or figure out a way to shorten them, because they are pretty handy.