Canon MARK III EOS-1 DS Instruction Manual page 24

Nomenclature
Attaching the Neck Strap and Hand Strap E1
Using the USB Cable Protector
Strap
Hand strap E1 (sold separately)
1
4
After attaching the strap, pull it at the buckle to take up the slack and to
make sure it does not loosen.
Attach the extension system terminal cap securely, making sure it is not
loose. Be careful not to lose it.
24
USB cable protector
2
5
Interface cable
Extension system terminal
3
Attach the strap
6
Terminal cap