Coventional Style Bulbs
These bulbs are of the conventional design, i.e. that have 2 small pin connections at each end

PLS Style Bulbs
These bulbs are of the PLS design, i.e. that have 2 small pin connections at one end only

Cyclone PLS Style Bulbs
These bulbs are simular to the PLS design, but instead of 2 small pin connections at one end, they have a screw thread at one end.

Smart Start PLS Style Bulbs
These bulbs are simular to the Cyclone PLS design, with a screw thread at one end, but are specific to the Smart Start UVs.