20 PCs Drop-in Anchors 1/4"-20 Zinc-Plated for Concrete, Secure Mounting, Industrial-Strength, Easy Installation - Internal Forced Expansion Screw Bolts for Solid Concrete

Getting ready to set some anti-vibration mounts that go under my air compressor. Will be using 8 of these anchors (2 per AV mount).I have some reservations about these anchors - they compare quite unfavorably to the Phillips and Redhead anchors I'm used to using That's a Phillips on the left in the side-by side photo.They are quite thin - a 5/16" hole for a 1/4" bolt. The other anchors I've used typically use a 3/8" hole for a 1/4" bolt, which means more grip area.No setting tool is provided. Fortunately I have one, so not a problem for me, but if you don't it could be an issue.The package of 20 was actually only 19 in the box, and 3 of those are missing the little wedge "bullet", rendering them useless. Fortunately, I only need 8.I think I'll try to use them, but will do a pullout test on the first few and switch to redheads (or upsize to 5/16) if I don't like what I see.

This is the first time for me using drop in concrete anchors.There is a metal pin inside that you hammer in using a setting tool, so that the anchor expands and grips the concrete which allows you to screw in your fastener without the anchor spinning around in the hole.Those metal pins are held in place inside the anchor with some kind of red wax. On several anchors, the wax had cracked so the metal pieces had fallen out and were loose in the plastic case.The setting tool was not included, and the instructions on the product page just says to "insert the thinner part of the tool" which was a head scratcher for me.Once I figured all that out, it was back to Amazon to order the matching-sized setting tool.The anchors held fast inside the concrete after the pin had been set with the setting tool, so the anchors work well for the light application I used it for. Also, I had to find the right length bolt.Too long and it bottoms out in the anchor.Overall, it works.