http://www.sw-performance.com/products/DeluxeMechTachs

http://www.sw-performance.com/products/WNGMechTachs

http://mechanicaltachometer.com/

http://www.superiorlabsinc.com/

http://www.aircraftspruce.com/catalog/inpages/mech_tachs.php

http://www.industrialinstruments.co.uk/html/mechanical_tachometers.html

http://www.britannica.com/EBchecked/topic/371894/mechanical-tachometer

http://www.checkline.com/tachometers/

http://www.stewartwarner.com/Catalog/tach5m.html

http://www.nisonger.com/mechanical-tachometer-conversions.htm