LED bulbs can directly replace the fluorescent lamp or energy saving lamps.

According to the different lamp bases and lamp cups, the LED bulbs are divided into several types:

E series: E26, E27, E14
E means screw base, digit number is the diameter(mm) of lamp base

GU series: GU10, GU20, GU24, GU5.3
GU is a type of bayonet mount base , digit number is the distance(mm) between the two pins.

So GU10 means 16 x 1/8=2 inches lamp Multifaceted （Mirror）Reflector lamp cup.

MR series: MR16, MR11
MR means Multifaceted （Mirror）Reflector, digit number is the diameter(1/8 inches)of lamp cup.

So MR16 means 16 x 1/8=2 inches lamp Multifaceted （Mirror）Reflector lamp cup.

PAR series: PAR20、PAR30、PAR36、PAR38、PAR46、PAR56、PAR64
PAR means Parabolic aluminized reflector, digit number is the diameter(1/8 inches)of lamp cup.
So PAR20 means 20 x 1/8=2.5 inches lamp cup.