Bushnell 7-21x40 Powerview Zoom Binocular is a standard size porro prism binocular which provides versatility, a great sense of depth, and particularly bright viewing at its lower magnifications. The focusing system is a lever instead of a traditional wheel, which many users find to be faster than other designs. It also uses a simple lever on the right side of the unit to adjust the magnification. This Powerview Zoom can provide easy viewing in low light or on an unsteady platform such as a boat when used at its lowest magnification.