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
Hi-Capa HPA/M4 adapter – Primary Airsoft
Primary Airsoft HPA M4 Adapter - YouTube
SOLD primary airsoft hpa m4 mag adapter | HopUp Airsoft
Pack HPA M4 mag adapter for Hi-Capa series
HPA adapter M4 charger for Hi-Capa series
STL file HiCapa to M4 - HPA Adapter・3D printing model to download・Cults