Reposted...original deal fell through: Filters plug in to ARGOSY I, II, OMNI B, C, TRITON IV, , OMNI V, VI and VI+ Filters also fit ARGONAUT 506, 509, 515 (No Plug-in) INRAD 2.1 SSB Filter Model 752 $99 INRAD 400hz CW Filter Model 753 $99 73 de KE4WY Jim