Qrity 20 Pcs Threaded Inserts, Threaded Inserts for Wood M4x15mm, Zinc Alloy Threaded Insert Nuts, Interface Hex Socket Drive

came fast, works good.

Our older dining room chairs became wobbly and I realized the original hardware was failing (the threads were breaking on the insert nuts). Carefully removing the old nuts and cleaning the holes out I was able to use these new bits and install everything nice and tightly back together.

These are quite tapered so I do not trust them in hard wood. I will only use these for soft wood like Pine. I run a sawmill and have my own customer furniture wood shop. I make live edge furniture. These threaded inserts are for attaching table legs to live edge slabs.I think that due to the extreme taper I will not trust these in hard wood though.One thing I am not happy with is that they say to use the "appropriately sized hole" but never mention what size that should be. This leaves me to experimentation for various wood types to get it right.

Got these to fasten a pedestal to a table top. There are no instructions on what size hole to drill, so I drilled several test holes and found that for these (M8x20mm), I needed a 3/8" hole. Also, you have to taper the top of the hole so that the insert will fit flush. If you don't, the lip of the insert is proud of the surface. These worked well for my application and I would recommend them.

These threaded inserts are doing a good job. Once piloted, insertion is done via a Allen. They thread into the wood easily and stop as they flange contacts the surface of the wood. The flange prevents the insert from sitting recessed to the wood so if you need a truly flush mount you may have to use a larger bit for just the flange diameter. Internal threads are perfect and once the insert is locked in place with some glue, they perform perfectly.

These have sharp threads on the outside, and the threads internally are smooth. Gets a good bite into the material.