The ECHO1 DSR / FS3 Selector Plate is the original part used by Echo 1 for the DSR. Echo1/JG parts are compatible with Tokyo Marui AEGs. Selector plates are an important part of the gearbox's operation. If a selector plate is misshapen or has a fouled metal plate then the semi or full auto function could be effected. If you're having fire selector problems it may be due to a bad selector plate.