(57) The invention provides a bulk transfer unit configured to enable a secure transfer of valuables from a first non-secure area to a second secure area. The unit includes a first door providing access to the unit from the first area and a second door providing access to the unit from the second area. The doors are separated from one another by a transfer area defined within the unit. The unit includes a locking mechanism providing for manual interlocking of the two doors such that access to the transfer area is restricted at any one time to access from one of the two areas. The locking mechanism includes a rotatable locking bar, which is rotatable between a first position and a second position. A handle is located on the secure area side of the second door and coupled to the locking bar and the handle is provided to enable a rotation of the locking bar. The locking mechanism further includes a first locking means for locking the first door and a second locking means for locking the second door. The rotatable bar is coupled with the first and second locking means, and in the first position the first door is locked and the second door is unlocked, and in the second position the second door is locked and the first door is unlocked.