Ultimate Arms Gear Phoenix Technology 20 Gauge/Shotgun Glowing Red & Green O.P.S. On Point Plain Barrel Front Triple 3 Fiber Optic Sight Mossberg 500/535/590/835/Maverick 88 Buttstock Shell Carrier

did not fit my 20 gauge Remington should have went with 12 gauge

It doesn’t give an option to pick the gauge of the gun. It arrived and though it snapped on to the barrel; I had to shave down part to the bottom and inside at an angle for the sights to align with the bead on top... so it really doesn’t fit after all... at least the shell saddle for my stock works (Always a silver lining).