Bentham Instruments Ltd. has developed a cooled housing for 28-mm side-window photomultiplier tubes (PMT). Designed for integration into light-measurement systems that require minimal dark current or temperature-dependent gain variations, the DH-00-Te has a minimum internal temperature of -25 °C with stability better than ±0.1 °C. Dark current is reduced by a factor of 100 for a multialkali PMT. For ease of mounting to other units, the housing has a separate plate that can be drilled and attached. Rigid, lighttight coupling is provided with minimal separation between the source and the photocathode.