Aetna Engineering, founded in 1968, is located in Grand Rapids, Michigan, and specializes in digital tachometers used on boats, ships, and in industrial applications worldwide. Their digital tachometers are designed to measure precise engine RPMs for efficient engine performance and are guaranteed accurate to one RPM. Aetna Engineering's products are used in various sectors including commercial marine, recreational marine, construction equipment, industrial applications, and military applications. The digital tachometers are constructed to operate in rugged marine or harsh industrial environments, unaffected by salt spray, water, sun, temperature, vibration, or aging.