The Origin Audio OA-2B compressor is constructed using Urei LA2a design. It’s an optical tube compressor/limiter built with high-end audio components, includes audiophile grade parts not found in the original LA2a, such as Holco metal film resistors, Auricap, Multicap, Solen capacitors, and Swedish made Lundahl audio transformers (input and output). This results in greater transparency than the original LA2a. Point to point hand wired. The T4-B optical unit is included. The OA-2B are stereo linkable.