AR North America AR20890 Mini-Matic 4/B Bolt-On Unloader Valve 2600 PSI by | Jul 24, 2026Part Number AR20890. Mini-Matic 4/B Bolt-On Unloader Valve. Type Bolt-On Unloader Valve. Bolt-On Design – Easy, secure installation directly onto compatible AR pump heads. Key Features. Outlet Connection 3/8″ Male.
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