374px-CloneDC15A swtcwvg
The Phase I Clone Trooper armor was worn by Clone troopers of the Grand Army of the Republic. It was bulky and less manuverable than the Phase: II clone trooper armor, and was hard to sit when wearing it. The armor's design was made from the Mandalorin bounty hunter Jango Fett. Most troopers wore this armor except for ARC troopers and clone commandos.
264px-Phase 1 Clone2 Wars Clone Trooper

A clone trooper in Phase: I armor in CW stlye