Bought these quite a while ago from WOOT and they work great in the garage for allowing me to easily and “precisely” park/position my car in the same spot every time. Mine came with lag bolts, these don’t (notice the teenie tiny print at bottom of the “easy installation” pic) though bolts are also not listed in the “In The Box” section. However I didn’t use them to anchor mine into the floor, I simply laid them on the concrete floor and they’ve stayed in place fine. Of course my car is barely moving when I make contact. I believe the weight of the car’s tire applying pressure to the guide’s angled surface helps to push down on the guide, helping to keep it from moving. Yet, I can easily move it by tapping/kicking it with my foot. That’s another thing I appreciate about these, I’ve changed their positioning twice thus far as I’ve added/removed more junk from inside my garage. Just park where needed and slide these guides into position touching the front tires. Wah..Lah! Simple but effective! Excellent purchase for my needs.
Thx this is useful.
Your wah lah, it’s “voila”. It’s French. Thx again
Sorry for my “faux pas”!
Some write “vwalla.” Not technically French, but 
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I use an old “Smart Park” bump in my garage and wondered if these would stay in place without bolting down. thanks for your feedback.