Solid-state lighting devices that utilize light-emitting diodes (LEDs) as a source of illumination and come with driver circuitry, optical, thermal, mechanical and electrical components. They are designed to connect directly to the branch circuit through a corresponding ANSI standard lamp-holder (socket) such as an Edison screw base, a bi-pin base, a GU5.3/GU10/GU24 base (twist & lock base), or any specialty base (R7s, SC, festoon, wedge, S14s, etc.) LED bulbs are mostly intended for use in lighting fixtures and can be in various shapes, include A (Standard), R (Reflector), PS (Pear Shape), MR (Multi-Faceted Reflector), B/BA (Bulged, Bulged with angular tip), BR (Bulbous Reflector), G (Globe), RP (Reflector, Pear shape), PAR (Parabolic Aluminized Reflector), T (Tubular), S (Straight-sided shape), and ST (Spherical Tubular). LED tubes serve as a replacement light source for traditional fluorescent tubes. Most LED light tubes are in the popular T8 form factor with a standard two-pin G13 base. T5 LED lamps have a G5 base (bi-pin with 5 mm spacing).