The format was mainly used for amateur cameras like the Brownie or the Zeiss Ikon Kolibri, with the Exakta SLR, the "Baby" Rolleiflex, the Yashica 44 TLR, the Komaflex-S SLR and the Primo jr as possible exceptions.
127 color transparencies can be mounted in standard 2" square slide mounts, and projected in an ordinary 35 mm projector.