Angel Custom AP10 M4 to MP5 9mm Magazine Adapter from Evike - YouTube
Modular WE-Tech M4 HPA Adapter V3 – Black Variable
Angel Custom AP10 9mm Airsoft AEG M4 M16 to MP5 Adapter Conversion Kit
Airsoft Evike.com - SMG mags or M4 mags? You don't need to choose with the Valken ASL! Comes with the SMG mag adapter so you can interchange = Best of both worlds!
Tactical M4 Speed Loader Inventory AK Vector Adapter for AK G36 MP5 Holster Magazine Accessories|Scope Mounts & Accessories| - AliExpress
The Gun Corner] M4 to MP5 Mag Adapter | Popular Airsoft: Welcome To The Airsoft World