The C7 is a variation of the M16rifle that is manufactured by Diemaco under license from Colt Firearms (ironically Diemaco has, in fact, been recently purchased by Colt) and used by the Canadian Forces, Hærens Jegerkommando (Norway), Military of Denmark (all branches) and the Royal Netherlands Army as its main infantry weapon.
The C7A1 (Diemaco C7FT) replaces the iron sight/carrying handle used on the C7 with a modified Weaver rail for mounting optics.
The C8 carbine is the carbine member of the C7 family, and in outwards appearance very similar to the Colt 653.