Birchwood Casey Universal Rear Bag Shooting Rest - This standard rear bag is meant to be used with the 4in center post on the rock, and other similar rests. Great rear rest to help steady your shot. Easy to pack and set up at the range. Since 1948, serious shooters, avid collectors and professional gunsmiths have relied on Birchwood Casey for shooting and gun care products that have stood the test of time. Birchwood Casey has pioneered innovative products with an unwavering dedication for quality.