I haven't seen the "box" type, but it sounds like one of these "slip-over" types with a stud at the rear to push down on the top cartridge to let you push a new one under the feed lips. I've used the "ring" type of loader before, and they are QUITE a bit faster to use; the assembly slips over the mag and locks in place with a spring steel tab, so the whole thing, mag and all, sits there quite securely. To use this one, you put your middle finger through the ring and press into the mag; this presses the top cartridge down far enough to let you drop a new cartridge into the front of the mag, then you lift the ring up to its maximum arc, and this causes a hook at the opposite end to push the new round into its rearward position, fully seated. HTH.