These free-float handguards are compatible with the Crazy Ivan Takedown Chassis, other brand takedown chassis, and original Ruger Takedown stocks. The handguards will also fit the Crazy Ivan Comp Chassis with the optional adapter, for a super rigid bench or 22 ELR rifle build. The 5-Slot size Handguards have 5 M-LOK slots on the side , 4 M-LOK slots on the bottom, are 10 inches long, and weigh just 6.1 ounces. The 3-Slot size Handguards have 3 M-LOK slots on the side , 2 M-LOK slots on the bottom, are 7 inches long, and weigh just 4.1 ounces. The Comp Chassis adapter weighs 1.1 ounce. There are anti-rotation QD swivel holes on the sides and bottom of the front end. These Handguards are CNC-machined from a single piece of extruded 6061T6 aluminum, so they are very tough and rigid. There are lightening cuts on the inside of the handguard that allow use of the Magpul X-22 Backpacker barrel block optic mount for optimum accuracy.