There are 2 manufacturers of these hoses and many places will call them a "concours" hose. Neither manufacturer make an exact replica of the original sight glass hose. The finish of the hose does not match, but the most obvious difference is that the sight glass itself has a hexagon shape instead of a square shape. If you would prefer a good used original, give us a call, we can usually dig one up for you. Remember to remove your coupler between this hose and the dryer, it will be need for reinstallation.
This hose is compatible with both 134a and R12 refrigerants.
Below is a picture of an original sight glass from a low mile 69: