Identification: Changeable bit key

[dzaengle]

Hello All,
I'm trying to identify the manufacture and any information on a changeable bit key I recently purchased.
The key is ~ 6 inches long. The bow is 1.5 inches wide and the brass bit is approximately 1 inch wide X 1.25 inches ht.
The key is made of brass with steel movable bits. Each of the three steel bits has numbered calibration marks that allow the user to record the settings.
By loosening the screw at the end of the shaft the steel bits move freely (tightening the screw secures the steel bits in place).
Each steel bit is crimped at the ends to prevent them from falling out of the key.
The bow has Prov. RI and "lettering worn off" Lock Co. on one side and Patented Dec.17.61 on the other.
Any info. on this key would be greatly appreciated. Please refer to attached photos.
Thanks,
Don