Dramm 400 Series Die Cast Water Breaker Nozzle is only meant to be used at the end of a watering hose and would not be used with a watering can. The dimensions of the nozzle are 1.111 inch x 2.222 inch x 3.333 inch, however the inside diameter is usually proprietary information to the manufacturer.
You may contact Dramm Corporation can be reached at 920-684-0227.