This is possibly one of the most common bulbs in boats and RVs. It is usually used in either interior reading lights, dome lights, and tail lights. They are also very common in trailer lights. The main variation of this type of bulb is the overall length of the bulb. The longer the bulb, it more light it outputs. 

Common bulb model numbers for this category are #67, #93, #97, #1003, #1141, #1156