For markers with serial # 893000 or higher (98 Custom/98 Custom Pro) SKU# T205002 The E-Triggerâ„¢ Electronic Upgrade Kit includes five firing modes (semi-auto, auto-response, full-auto, 3-shot burst, turbo) that can be changed in seconds for rapid (up to 15 balls per second (New ASTM Standards)) firing. Requires 9-volt battery. Does not work with 98 Custom. Available on: Custom Proâ„¢