Since the release of the Source Four, other lighting manufacturers have since revised their products to compete in the market share alongside the ETC. The Selecon Pacific, an L shaped ERS, has an irregular shape due to an integrated dichroic cold mirror, which effectively splits the visible wavelengths of the light beam from the infrared, allowing the heat to be drawn off by a heat sink and away from the instrument. This keeps the beam of the fixture cool allowing for the use of plastic gobos. The beam also improves shutter, gobo and color gel life, and can improve the temperature on stage. Altman Lighting released their Shakespeare line of units in 1994 as a response to the Source Four. One improvement over the Source Four is a wider range of adjustment in regards to rotation of the barrel assembly. The patents for some components in this unit have been licensed from ETC.