This is the Doepfer A-103. At $109, it is one of the cheapest fully fledged Eurorack filters. It is an excellent 18db transistor ladder with progressive overdrive on the output state and
Modular Synth Tutorial: Eurorack Filters: Which and Why
Minimoog VCF clone
MATRIXSYNTH: Aion Modular 904A Moog Filter in Eurorack Format