The "Plan-B" by Q is designed to replace the mounting hardware on the rear of your silencer.  Here is a quick (but not exhaustive) list of which model fits what silencers:

• Alpha - 1.125x28 - This model will fit many pistol silencers like the SiCo Alpha mount silencers (Octane, Omega K series, Harvester) as well as pistol silencers like the Rugged Obsidian, Griffin Revo/Resistance, etc.
• Bravo - 1.375x24 - This model will fit SiCo Bravo mount silencers (Omega 300, Hybrid, Harvester BB) as well as many others like the Dead Air Nomad, YHM Resonator R2, Torrent silencers, etc.
• Charlie- This mount will fit SiCo Charlie mount silencers like the Sakers and Chimera.