Recommended but with a caveat - Midwest Industries AR-15/M16 M-Series Two Piece Drop-In M-LOK Handguard

As the other reviews will attest, this is a well-made and solid hand guard. It is truly 'drop in' for a standard m4 carbine and I doubt most will need any type of delta ring tool to accomplish the install as it's installed one side at a time, so I don't find it to require any herculean strength to get the job done. It's a solid piece of equipment, well finished and obviously of quality, and it locks up solidly. It also is of a diameter on the smaller side, so it's not nearly as large as many quad rails etc.

My one complaint is that it really needs a small interlocking boss or set-screw arrangement, one per side, to lock the two halves together once installed. If you plan to install a vertical or angled fore grip, the problem I encountered is that under use and recoil, the bottom half slides back and forth very slightly as the vertical grip adds leverage. This is a disconcerting feeling. I do not encounter this issue on something like a Magpul moe drop-in, for example, because the two halves of that product lock together once in place.

Ultimately I returned it, but felt a bit badly as it definitely is very high quality. If you do not use any type of fore grip, I suspect you will be ultimately quite happy with this.