TK Audio MB1 500 Series Stereo Processor Mini Blender - Boxed

Solid State Logic SSL 500 Series G-Series Stereo Bus Compressor Module

Nekotronics Busscat - 500 series Mix Bus compressor

IGS Audio 576 Blue Stripe 500 Series 1176 Rack Mount Compressor Peak Limiter #1

IGS Audio One LA 500 Series Tube Opto Compressor Module (LA-2A-style)

Solid State Logic SSL 611EQ 500 Series EQ Module

Trident SC2-500 500 Series Optical Stereo Compressor

Empirical Labs EL-DS DerrEsser 500 Series De-esser Module - Boxed