The rifle was supplied from www.acmgear.com and after discussing the new rifles they had in stock, they said that they wanted a better opinion on the M4A1 from Jing Gong.
RA-Tech WA/AGM NPAS Kit
The NPAS kit was supplied directly from RA-tech in Taiwan. Their customer service is pleasant and friendly. They had already noticed from my website (in my email signature) that I had an AGM M4 and advised me on what part I would need.