It is not an ideal situation to have to do a battery change in the field, but get yourself a small waterproof box and bring along a spare battery and o-ring for your transmitter! Don`t forget you`ll need some silicon grease for the o-ring before re-assembly.
NOTE: It is recommended that you always change the o-ring at the same time as the battery.
CAUTION: Ensure you have proper training to maintain you own equipment, Diving Solutions holds no responsibility for mis-use, damage or injury caused by using this item. If your not sure, please check with a trained professional.