Acetech Lighter BT (Bluetooth) Tracer Unit that will let you shoot lasers and chrono your gun at the same time. 

The Specs:

• Lighter BT can connect via Bluetooth and can act as a chronograph - it will even log them for you to reference later
• Works with green and red tracer BBs
• Sustained rate of fire up to 35 BB rounds per second
• Rechargeable built-in Lithium Polymer battery; fully charged battery will last over 30,000 rounds
• Auto shutoff after idling for 2 hours
• One M11 clockwise thread adapter/and one M14 counter-clockwise thread adapter

Need tracer BBs? We have them here.