Adjustable non-compensated Dual CO2 Flow Meter that allow our customers peace of mind that the flow being displayed is accurate regardless of the variance of incoming pressure. Allow the user to adjust the flow based on the cages displacement size for faster results. 512 describes the flow rate range 0.5 to 12 LPM. Ideal for single cages varying from mice to guinea pig. BR is for Wall Bracket. Don't know the fitting coming from the wall? No worries the wall bracketed flow meter attach to a wall via two screws and we provide you an open input hose with clamp that simply slides over the spicket and clamps the hose in place. The wall bracket is ideal for forged turrets that are non-removable. The Wall Bracket (BR) includes a wall bracket as well as both input and output hoses with a quick disconnect for easy connection to our lids or induction chambers.