350Pcs Threaded Inserts M2 M2.5 M3 M4 M5 M6 Female Thread Metric Knurled Nuts Assortment Kit Brass Heat Set Insert for Plastic and 3D Printing Components

Very nice product. I 3D print and have often used these brass inserts to add a screw socket to my prints. I used to buy them individually and spend as much on just a couple as this entire box. So nice to have a bunch in hand for future use!! To use them, create a hole in the print slightly bigger than the screw size. For example, M2 gets 3mm hole, M2.5 gets 3.9, M3 gets 4.7, M4 gets 5.0, M5 gets 7 and M6 gets 8. That is all the sizes in the kit. BTW, this info is vital, since that info doesn't come with the kit and has to be researched online. Thank me later.... Once you make the hole, at least as deep as the knurled part of the inset, preferably as deep as the entire insert, you insert it with the smooth end first and push it in with a hot soldering iron. If the thickness of the plastic is exact, you can push it in from the back and it is slightly easier to use thereafter. Alternatively, I've had good success pushing it in with a vice in ASA and then heating with soldering iron afterwards to melt the plastic around the insert. While you can pull them out after installation with extreme force, they are very strong.

Product as described! Have not had even one fail on me. I would like to mention I am not easy on the things I print. I have even used these to repair injection molded pieces with self-tapped screws that stripped out. Great product end of the different sizes even further expand your options for repair options

Have used these in numerous 3D printed plastic parts, and they seem to work great. Pull out strength is good. Heats up quickly. Can be recovered if you mess up the insertion. Very nice.

Perfect product, perfect handeling and delivering

It's held up very nice. I haven't had any issues with how it held up in my prints.