The PET-2100 DX is the latest in tachometer technology. The processor updates engine RPM info 20 times per second and is accurate within 10 Rpm. The compact, lightweight casing and the clip-on inductive pickup spark plug attachment make it a snap to install and remove after testing. The tachometer will monitor engine Rpm on Two-stroke 1-4 cylinders, Four stroke 1-8 cyl, and offers compatibility with all aftermarket ignition systems. Not just a tachometer, it comes with Peak Rpm recall, Total operating time, Dual display for current and maximum Rpm and the ability to recall two maximum Rpm memories for comparison. The wide selection of modes and trouble free operation will appeal to all tuners and mechanics. No wires to install, automatic on-off operation and simple function operations make this a welcome addition to any toolbox.