Burris solid steel rings not only ensure accuracy, they provide an extra measure of confidence and peace of mind. Machined from a solid blaock of steel to exacting tolerance, each top and bottom are matched for strength and fit. Designed to handle any rifle and any recoil from rimfires to magnum calibers. Burris offers a wide selection in 1" and 30mm. Mfg: Burris Measurements are from the bottom of the scope tube to the bottom of the ring: 1" Low .130", Med. .255", High .450". 30mm Med .205", High .330"