The J50 provides a nearly flat spectral response from UV to Far IR due to the absorptive black organic coating. The J50HR utilizes a partially absorptive metallic coating. This results in faster heat transfer and significantly decreases the time constant, allowing these models to be used iat very high pulse repetition rates. Sensors with an LP in the product name are low profile, working well in tight spaces. The J50LP-2, J50LP-3 and J50LP-3 all have an integral UV quartz diffuser; this provides some laser attenuation and beam spreading , thus extending their pulse energy range.