Only works with their upper receiver, the worst customer service - Jacob Grey Firearms AR-15 M-LOK Handguards

Put this handguard on 3 different upper receivers and it would not torque down and would wiggle on all 3. Contacted JG who are incredibly smug and terrible at cs and assumed I didn't know how to use a screwdriver. Sent it back to them, low and behold works fine on their upper ( which they didn't send back with the handguard because then it wouldn't be in a landfill now). Will never buy another JG product ever again and will recommend any who ask against it