Complex sentence: The SIG SG 552 is a compact version of the SIG 550 5.56 x 45 mm NATO assault rifle manufactured in Switzerland by SAN Swiss Arms, formerly Schweizerische Industrie Gesellschaft (SIG).
Split into simpler sentences: The SIG SG 552 is a compact version of the SIG 550 assault rifle, also chambered for the 5.56 x 45 mm NATO cartridge. It is manufactured in Switzerland by Swiss Arms, formerly Schweizerische Industrie Gesellschaft (SIG).