Bases are selected to match the designed rake angle of the pole light with the number of pins (electrical contacts) necessary. Rake angle of 0 and 5 degrees are common on later production boats, 16 degrees are often found on pre-1980 year boats. All-round pole lights use 2 pins, and removable combination masthead and some plug-in bi-color pole lights with an accessory light require bases with 3 pin contacts.