Standard 9V battery instead of costly little watch battery.And also increases your safety,since you can take accurate reading farther away from the propeller. You will be able to peak engine performance by measyring rpm,in a 10-99990 rpm range. Regardless of whether you are using 2-3-4-bladed propeellers or checking capacities of
RX 4.8 and Tx 9.6V battery packs.
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