The 9773-K Valu Center Mirror Mount achieves a high level of stability by using a 1/2 inch frame that is stiffer than any you'll find on other comparably priced 1.0 in. (25.4 mm) diameter mounts. Two Allen-Key adjustment screws give you ±4° for tip and tilt adjustments using the same high-quality proprietary screws, brass nuts, and hard sapphire seats found in all New Focus® mounts.