[Quentin]

That's a terrible price for a DPMS kit. And they may call it milspec but DPMS usually sells a commercial kit, which is what appears to be pictured there. If you can find anyone who has stock, try to get a milspec kit. PSA and BCM used to have much better kits for less money. PSA even had a kit with a MOE or CTR stock for not much more than that thing at Brownells. I know it's a bad time to be looking but don't settle on high priced junk.

As Sputnik said, a standard stock wrench will work on rifle and carbine receiver extensions.