||I got this yesterday with a bunch of SiG stuff in a nice self-birthday bundle. I tried it on my JG 552 for a spin and it fit nicely. I popped it on the ICS and it became clear that some modification was needed. Some minor dremmeling (not recommended. will void warranty on part) and a couple minutes later, this RIS slipped right on with no adverse affect. A side note is that this RIS is beefier than it looks. Its a little chunky, but I find that its better. The feel of rails in your palm is actually not very uncomfortable, and buying rail covers might add to the bulk a little. All in all this is a fine piece of kit if you are into SiGs a lot.
Excellent fit and finish
Surprisingly comfy to hold
added area to mount optics, lights, etc
For ICS Sg552 installation, slight modification is required as warned by evike, but I'm almost sure that it will void the warranty.
Other than that, this is a great item for any *compatible* Sg552.
*Will give 4/5 only because of the slight modification that may be necessary for the ICS.