The GrovTech heavy duty Push Button Swivel Bases are deigned to work with the GrovTech Heavy Duty Push Button Swivels. These are designed to be countersunk into the stock. Perfect for the shooter who often removes their sling. The heavy duty push button bases provide rock solid lock up under event he toughest conditions. Specifications and Features: GrovTech Heavy Duty Push Button Swivel Base GTSW-289 Push Button Base Heavy Duty Stainless Steel Black