The Accuracy International (AI) .300 Win Mag Sled inserts in place of the rifle magazine to allow easy loading of single rounds. CNC-machined device ensures proper cartridge alignment and reliable feeding. Supports new shooter instruction and controlled firing of single rounds in long range and competitive environments. Feeds .300 Win Mag caliber rounds. Made from durable, self-lubricating, long lasting DelrinŽ. Will not scratch, mar or dent metal rifle parts. Fits the Ruger M77 Hawkeye in .300 Win Mag only. Made in the USA.