You searched for "variable frequency"
RS PRO
RS PRO Counter Counter, 6 Digit, 20kHz, 230 V ac
Part: 808-6617
Electronic counter measures time intervals and frequencies up to 20 kilohertz.
RS PRO
RS PRO Counter Counter, 6 Digit, 20kHz, 230 V ac
Part: 808-6627
High-frequency impulse counter with LED display and relay output for industrial process control.
RS PRO
RS PRO Counter Counter, 6 Digit, 20kHz, 230 V ac
Part: 808-6605
6-digit panel-mounted counter measuring frequency up to 20 kHz with relay output.