Our kits are modded from existing airsoft parts that we purchase from airsoft stores. They are a combination of existing Tippmann X7 parts, airsoft parts, and in some cases real-steel parts that we modify to allow them to be useable on your X7.
The 552 kit is comprised of a foregrip, 1 piece magazine/magwell, folding stock, and airsoft 416 rear sight. The 552 foregrip is intended for use with an 8"-10" barrel. This build is perfect for you operators that like a nice and compact setup.
The Scenario Arms Scenario Arms X7 SIG552 Kit is newer, so it should be commonly available, both new and used.