Gibraltar SC-MCSA6 6" Cymbal Stacker

I would consider taking the 6" over the 4" if the underlying cymbal is not much bigger than the top cymbal.

If the underlying cymbal is much bigger, the 4" will do.
Except... when you want to hit the bell of the underlying cymbal...in that case, the 4" will be too short.. So decide what you want carefully.

These stackers are great to exploit a minimal setup and still use more cymbals.

However: when you screw it on the cymbal stand, I can't tighten the underlying cymbal anymore. No more space for the nut.
That underlying cymbal just hangs loose, only with a felt for some protection, but the nut to fasten it doesn't fit anymore, so little diameter cymbals will move around more than it should, let alone what happens with big cymbals which are unsecured with a top nut.

So to secure the underlying cymbal, you'll need to use a less bulkier nut than Gibraltar uses, maybe also less bulkier felts, and the problem is solved.
(that's why you should always have a bucket of that spare stuff lying around)

Cheap, solid and wonderfully usable.

This great little product is a boon to drummers who want to add more cymbals to their kit without taking up space. It works, and is made perfectly, as is to be expected from Gibraltar.

Using either the 4" or 6" stacker, one can put splashes over crashes, bells over trashes, small effects cymbals over trashes over rides. The possibilities are endless. Just make sure smaller cymbals go over larger ones.

Be warned though, upon trying one for the first time, you will want to buy one for every cymbal you have, so small is the footprint and so effective the result.

I did use a Gibraltar cymbal stacker with side screw, which eventually chewed up the threads on my cymbal stand. Got a new cymbal stand so tried this as a replacement as it is threaded and not side screwed.
Really high quality, felts and wing nut really good. My only complaint is that sometimes mid gig I have to re-tighten it onto my ride cymbal stand as the vibrations caused by my ride cymbal cause it to loosen slightly. This could be prevented by having some kind of nylon somewhere in the threads, much like a locking nut has. However this would probably push the price up if they made this adjustment! Still, very good though!