We found that shooting with the Z-Cam S1 and S1 Pro - mounting the camera directly on top of a monopod required us to engineer all kinds of hacked together spacers - and there was no easy to use spacer on the market.
So we made a few prototypes and settled on a design we liked.
Hard black matte anodized.
3/8" female threaded top and bottom.
Easy to grip.
Each spacer ships with two (2) standard 0.75 inch 3/8"x16 threaded set screws.
We thought about permanently attaching them but you can do that easily enough yourself with Red loctite.
Cool CNC engraved logo.
Buy one - or maybe a couple for your friends.
BTW the size is 1 inch diameter, 2 inches high.