This is the tach to have in the dirt world, including sprints, and is coming on strong in asphalt. QuickTach features include: 

.75 x 1.75 Digital Display - 
Aluminum Waterproof Case - 
Mounting brackets - 
Backlight that comes on when the engine is shut down and auto-off to conserve battery life. - 
Highest RPM display automatically for 15 minutes when engine is shut down. - 
Tach automatically clears and comes back on when engine is re-fired. - 
Reset button for those times when you want to reset during a run. - 
Self powered by a 9V battery - 
Low battery indicator to monitor your 9V power supply.