The meter size and year of manufacture is clearly marked on each register face. For residential use, the M20USG is, by far, our biggest seller. Of course, with a large yard and sprinklers, etc then a larger meter such as the M41USG and M50USG might be needed. Many are still in existence in cubic foot measurements and some water companies still use the cubic foot measurement instead of in gallons. The M60 and M80 do not require special meter couplings as those two models have standard female threads.
Most people know what the horizontal model is like.
The vertical styles are a special-order item and will be shipped directly from the factory. On a vertical installation, if the water source is coming from the ground and going up, we call that the up-model. If the water source is coming from above and going down, we call that the down-model. The down model will work but you then have to read the meter upside down. We prefer to sell the larger sizes only after you have provided the gallonage and other vital statistics needed.