Every CHRONY measures the speed of bullets, arrows, shotguns, even pellet-and- paintball guns.From 30fps to 7000fps and with better than 0.5% accuracy. Just unfold like a book, mount on a tripod or place on the bench,insert the diffusers and start measuring speeds within minutes. Every CHRONY is made of 20gauge steel but weighs less than 2.5 lbs. When folded they are only 7.5" long, 4.5" wide by 2.75" high. All CHRONYs come with a 5 year limited warranty, but will last a lifetime. The MASTER CHRONYs have the same capabilities as their respective SHOOTING CHRONY counterparts, in addition that, the MASTER CHRONYs have a moniter which brings the LCD right up to the bench { close }away from the projectiles path. It also doubles as a remote control.