Apollo Horticulture Purple Reign 6W MR16 LED Grow Light Bulb for Plant Growing 1 - Apollo Horticulture 6W M16 LED Grow Light Bulb Dimensions: 2.50" Height, 1.75" Diameter / LED Wavelength: 430nm - 660nm Attain optimal photosynthesis - purple light combines ideal red and blue light spectrums for healthier, more abundant grows High power without the heat - large wrap-around heat sink keeps unit cool Plug-and-play - fits standard E27 sockets for easy installation, no special hardware necessary