C3 for <6 contacts using single blocks in front mounting
C4 for <6 contacts using single and double blocks in front mounting
C5 for <5 contacts using single blocks in front mounting
C6 for <5 contacts using single and double blocks in front mounting
C7 for <4 contacts using single blocks in front mounting
C8 for <4 contacts using single and double blocks in front mounting
C11 for <3 contacts using single blocks in front mounting