The Spacer light was designed from the ground up to improve your ride. Sparse lights are constructed from die-cast aluminum, not plastic. Once installed, they are part of your bike. They won't jostle, rattle, or interfere with your cables. The metal chassis is joined by a double-lens, sealed with a silicone gasket to keep everything dry inside and working for a very long time. They're solid, sealed, tamper-resistant, and stupidly bright.
The Spacer Light sits beneath your stem in the stack of spacers. The light fits both 1" and 1 1/8" steer tubes. This integration makes it extremely difficult to steal and keeps the light pointed in your path of travel, visibly seated above the shoulder line of cars, and generally out of harm's way.
The Tail Light slips on and clamps down on your seat post. It fits the most common seat post sizes - anything from 27.2mm - 31.8mm. There is no way to remove the light without removing the seat post. The source of illumination in the Tail Light is a series of board-mounted red LED's - 4 face rear and 4 to the sides. In total, they add up to 1 Watt of output (about 30-50 Lumens). The Tail Light has 3 modes, On, Off, and blink.