This is Sling Mounting Kit for the Remington 870 Express Shotgun in 12 Gauge. Comes with everything you need to attach a sling to your shotgun.
QD REM-870 EXP CAP(with internal mag tube ratchet-type system)
Replacement magazine cap with swivel base,3/4" wood screw buttstock swivel base and two super swivels.not for 3.5"mags
Fits: SWIVEL/CAP SET,REM EXP 12GA

Product size: Screw diameter 31mm, inner diameter 24.4mm, height 51mm Material: Steel
Package includes:1x Sling Mount Set
Details: Fits Remington 870 Express Shotguns in 12 Gauge
Ratchet Cap for External Ratchet System (870 Express Models)
1" Bvawtrs Quick Detach Sling Swivels
Buttstock Swivel Stud Base & Washer