Mont. Code Ann. § 32-2-919

A mutual association may conduct a safe deposit department. The liability of any mutual association for the safekeeping and protection of the contents of safety deposit boxes is determined by the contract endorsed on the receipt delivered to the renter of a box at the time of the rental. However, the obligation of the mutual association is limited to the exercise of ordinary diligence and care to protect the contents of the box from loss or damage by fire, theft, or other causes.