This is a Calico® M-905 speedloader for 9mm 50-round or 100-round helical magazines.
Calico helical magazines hold a tremendous amount of ammo in a compact package, but stuffing them full by hand is tedious at best. This hand-cranked speedloader accepts a full box (50 rounds) of 9mm ammo at a time and holds the magazine in place during loading operations. Ammo in the hopper is clearly visible through the clear side plate on the speedloader, enabling you to keep track of how much has been fed into the magazine. Sturdy construction and reliable operation ensure that you’ll be using this to rapidly refill your Calico mags for years to come. The Calico M-905 speedloader works with the M-913 (50-round) and M-912 (100-round) 9mm magazines only.