They are supposed to fit a Mach 3 handle but they definitely don't. You can see that there are groves cut into the holes of the handle so that these cartridges purposely don't clip in, while the larger clips on the Gillette cartridges do. Maybe there are older style machines three handles that these fit, but they don't fit modern machines 3 handles from the last 5 years or so.

I have been using these Life Brand razor refills for several years now instead of the original Gillette Mach 3 blades. I have had no issues with these refills clipping into my original Mach 3 handle. Yes, these blade cartridges are a bit thicker and that does make it a little tougher for close trimming by your nose. Never had a sharpness issue & I rarely have had any razor burn (I do use sensitive skin shave gel). The price of these Life brand replacement blade cartridges far out weigh the differences to the higher quality & shape of the original higher priced Gillette blades. I love Gillette products but all razor brands have ridiculously expensive replacement cartridges. I will stay with these & highly recommend.

Maybe other reviews had a bad batch of blades, I had no issues. They fit in Mach3 handle, not at the same angle as the originals, the gel is not as good and somewhat more cumbersome, so you have to pay attention to reach the hair near your nose, but they do the job and stay sharp for quite some time.

They do fit a mach 3 handle but the angle is slightly different and they are thicker but did a good job

This claims to fit Mach 3 razor handles but doesn't do so.

These cartridges don't fit a mach 3 handle, although it explicitly says that on the box. They don't "clip in" and so fall off immediately. Don't waste your money.