C6: 114mm x 162mm - suited for an A5 folded once or an A4 folded twice into quarters.
DL: 110mm x 220mm - suited to an A4 folded twice into thirds
DLX: 120mm x 235mm - slightly larger than DL to allow thicker content
C5: 229mm x 162mm - Suited to A5 unfolded or A4 folded once in half
C4: 324mm x 229mm - suited to an unfloded A4 or A3 folded once in half
B4: 353mm x 250mm - slightly larger for thicker set of A4s