According to cap and bulb size there are following types of direction lamps:

1. T – mini cap lamp (ex. T 4 W)
2. R – lamp with 15 mm cap and 19 mm diameter bulb (R 5 W)
3. P – lamp with 15 mm cap and 26,5 mm max diameter bulb (P 21 W)

The following letters are used for direction lamp cap type identification:

1. P – flange lamp;
2. BA – lamp with pins, situated symmetrically to each other;
3. BAY – lamp with pins where one of them is shifted height along;
4. BAZ – lamp with pins where one of them is shifted height along and radially;
5. SV – tubular lamp with caps on both sides;
6. E – lamp with screw cap;
7. W (before figure) – lamp with glass cap.