The old-school Hobbico Digital Mini-Tach has been around forever; it worked well but was limited to 2-blade and 3-blade propellers and ran on AAA batteries. Hobbico has just updated this classic tach with a brand new version that features a long-lasting CR2032 Lithium-Ion battery, and supports propellers from 2-9 blades. The Hobbico Mini Digital Tachometer displays dynamic rpm's and saves maximum rpm's as well.
This unit looks to be a nice upgrade over the original and should come in handy for all of us that tune the engine based in part on maximum propeller rpm's. The Mini Digital Tachometer retails for $24.99 and is in-stock at Tower Hobbies.