With this added BP-E1, your CANON EOS system now has a few solutions in providing various means in supporting professionals at work, regardless where they are.
The camera doesn't require turning off while performing the power source switching but it is not advisable to do so when camera is activating other task such as film transport modes like power film rewinding etc.. The accessory can also be used not just for the EOS-1N but on others such as Canon EOS-1NRS, EOS-1V and even EOS-3 etc.
The battery grip pack
Cosmetic: Good condition, with little signs of use.