I went to see Jojo Mayer & Nerve play this past week at a local club and got to examine his Sonor kit close up. I noticed a very cool looking stacker ring set on his 2nd snare and had the opportunity to ask him directly what it was. I blogged about it here
Basically it's a prototype he's working on with Sabian that is comprised of 2 rings cut from cymbals, stacked on top of each other. The top ring has holes drilled about 1-2" apart. The sound was cool - think 1980's cheesy drum machine but with a cool acoustic undertone.
Would love to see this go into production. I uploaded some video from that night here