1) Auto dial 2) Auto gauge 3) Buckle clasp 4) Dash device 5) Dash dial 6) Dash feature 7) Dash gadget 8) Dash gauge 9) Dash instrument 10) Dash instrument briefly 11) Dash part 12) Dashboard device 13) Dashboard dial 14) Dashboard instr 15) Dashboard instrument 16) Dashing revolution monitor 17) Dial for rpm 1) Tachograph 2) Tachometer 
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Abbreviation of the term Tachometer (a device that puts out pulses as the tape moves in a tape deck).
Tachometer