Wide Duplex® RE
Place game of approximately 16" in height in the ranging bracket on the lower picket, and turn the power selector until it fits into this space, then read the numbers on the rear of the power selector ring to get an estimate of the range (“3” for 300 yards, etc).
The duplex may give you a ballpark estimate if you only hunt smaller deer.However if you hunt large deer,elk or moose,the duplex method is pretty much useless.