JE Machine Tech AR-15/M4/M16 Flip-Up Polymer Front and Rear Sight Set Black PS-PS7B. For more great deals on AR 15 Parts by JE Machine Tech please browse our J & E Machine Tech Gun Parts page. What firearm models does the manufacturer say JE Machine Tech AR-15/M4/M16 Flip-Up Polymer Front and Rear Sight Set is compatible with? The manufacturer says that JE Machine Tech AR-15/M4/M16 Flip-Up Polymer Front and Rear Sight Set is compatible with AR-15 M4 M16JE Machine Tech JE Flip-up Front And Rear Polymer Sight Set Black