My Panel 20 had a 16A MCB/RCD mounted on an ISO rail. I moved it to a consumer unit and filled the hole
exactly with two hour counters from the same manufacturer as the ones detailed in the instructions on the Download page.
However, I got the cased type that you can reset, so can I reset one whenever I feel like it (say at the start of a trip), and the other is reset when I fill up with fuel. They are wired to turn on when the instruments are on, and count when the ignition is on.
The cases had to be cut down a bit to fit one above the other, and I fitted a couple of reset switches underneath.
The model number is 701 F/T R xxx x 0512D
Curtis 700 Series