Mine is mounted with velcro, there is a button on the back that will recall info, if you do not catch it in time.The SenDEC Fastach is much better as it has a memory. The TTO only holds the RPM for a few seconds after you shut off the engine. I forget to look a lot of times! The SenDEC Fastach is a little higher priced but I think it is worth the extra. Both will do the job.