This Protektor Wide Owl Ear Front Shooting Rest Bag is for use on a mechanical rest. The Protektor Wide Owl Ear Front Shooting Rest Bag is designed to handle the forends of larger rifles with flat forends around 3". The bag comes with a standard fill of regular sand weighing 1.2lbs. The bag measures approximately 2-3/4" - 3" in between the ears and has a base size of 2 1/4" W x 5 3/4" L x 1" H.