PelletgageR is designed to efficiently sort pellets by head diameter. Choosing two gages will allow you to eliminate any pellet over the larger size, and under the smaller size. For instance, if you want 4.52 mm pellets, choose a 4.53 and a 4.51 PelletgageR. You will first put a batch (up to 48) pellets in the 4.53 gage, and shake them around to get them to enter the apertures. Use a finger to get them to drop into the plastic guide plate vertically. If the pellet head does NOT drop into the gage plate, then it is >4.53 mm in diameter. Remove those pellets, and take those that drop through to the 4.51 PelletgageR. Repeat the process with the second gage. Any pellets that DO drop into the aperture are <4.51 mm. So you now have yielded pellets near your ideal size. Most .177 pellets are sold as nominal 4.52 mm head size. This is a fast and accurate method of getting more precise pellets for serious use in competition or hunting.