Browning Double Helix T-Bolt Rotary Magazine - Calibers: .22 Magnum and .17 HMR - Capacity: 10 Rounds - Slimmer lighter and easier to handle than the competitions rotary rimfire magazine the ten-round Double Helix uses a torsion drive spring and interlocking gear design to maintain correct timing and exact cartridge alignment for smooth reliable feeding. The translucent gray body allows for easy verification of the number of remaining cartridges. Ammunition can be removed by moving the exposed gear back slightly to gently drop each cartridge without tools or scraped fingers The smooth rounded exterior contours of the Double Helix along with twin gripping grooves tapered shape and a slightly extended baseplate design make insertion positive while the spring-assisted drop-free magazine ejection feature allows for rapid magazine changes. The new Browning Double Helix rotary magazine system is easy to load easy to carry and easy to use. Most of all its easy to see the Double Helix magazine design is the shape of things to come.