I know a lot of people hate the Primary Airsoft adapters, but when it's 110° outside, a light kit is a life saver. Also a great first step into HPA : r/airsoft
HPA M4 mag adapter for Hi-Capa series
Download STL file HiCapa to M4 - HPA Adapter • 3D printing model • Cults
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Primary Airsoft Products - AirsoftJunkiez.com
SOLD primary airsoft hpa m4 mag adapter | HopUp Airsoft
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