Review on LOKMAN 105PC Rivet Nut Assortment Kit With Flat Head Carbon Steel Threaded Inserts - Includes 8-32UNC, 10-24UNC, 1/4"-20UNC, 5/16"-18UNC, And 3/8"-16UNC Knurled Body Rivnuts (Rivet Nut Kit 2) by Bill Schlag

Sounds like a lot of these reviews are by people who have just learned what a rivnut is.I can appreciate their enthusiasm but if you're using these for an important joint, it may be better to stick with more reputable suppliers.I bought 2x 100 1/4-20 rivnuts. Spec says grip range is 0.040 - 0.140" and pilot hole diameter 0.356",First of all, I don't know what drill 0.356" is supposed to be.that does not appear on my drill chart. But it's a hair bigger than 11/32 so I drilled pilot holes at that size and had to tap the nuts a bit to get them in the hole. In case you don't know this: 11/32 drills are not in common "hardware store" drill bit sets -- you'll probably need to buy a drill to go with your rivnuts. The pilot hole needs to be carefully-sized; if you go up to 3/8 the collar forms unevenly, partly falling "inside" the hole.I did tests In 0.065" wall square tubing, so I could look in the end and see how the nuts compressed. At that thickness they worked fine. As you get to the top of the clamping range though, things fall apart. For material thicknesses over 0.100, the collar would form up inside the drill hole, rather than on the backside of it. Therefore these nuts were hard to thread the install tool out of, hard to thread fasteners into, and could actually just pull right out of the hole with a little wiggling.For the price, it's worth your time to waste a few nuts making test joints and cutting them to verify they actually hold. You need to see a fully-formed "collar" around the backside of the material these are installed into. I returned my unopened bag but kept the first one for "dinky" uses -- For my main project I got quality hardware from Fastenal and McMaster. Something to think about: the Fastenal rivnuts I got had a larger body diameter by 0.047", which is 3 drill sizes larger than these for the same thread.wonder which ones are stronger, eh?