Takes the same frame blocks as found on Phantoms (or more correctly, both guns use the same AR style grip lug). Haven't seen an ICD specific grip block in a few years, and I snagged that one to put on my ATS
. A CCM 86 grip block would be quite awesome on a cat.
Look for a well ported barrel, they have a lot of potential to be a freakishly quiet gun. The stock barrels have a bit of a pop to them, but the ICD threaded Freak with an All American tip I use on mine is rather scary in how quiet it is.