Found this stacker in Kelly Gallup’s Slide Inn fly shop on the Madison.
They come in about 4 sizes.
Kelly swears by them.
You put the hair in the hole on top. Tap the device a few times. In your hand, you turn the devise perpendicular to the table, twist the top part (on a swivel) and extract the stacked hair. Seems to work well.
Been around for quite a while, although perhaps not widely available (local to my area). When first introduced they cost a fortune, but looks like John has gotten the price down. Used mine for a couple of flies, and then put it in the bottom drawer. Nice idea, but more cumbersome than a standard hair stacker. Yet another questionable attempt at the better mousetrap. YMMV.