1-1/2" from center of mounting hole to center of mounting hole.  Overall length is 2-1/8".
Choose color from drop-down menu.
Reference Numbers:
Transparent Red - Williams #03-7034-9, Data East/Sega/Stern #550-5036-02, Gottlieb #A-9394
Transparent Blue - Williams #03-7034-10, Data East/Sega/Stern #550-5036-05, Gottlieb #A-9394B
Opaque White - Bally #C-693, Data East/Sega/Stern #550-5036-08, Gottlieb #A-9394
Opaque Red - Williams #03-7034-4, Gottlieb #A-9394, #A-9394R
Transparent Yellow (not pictured) - Williams #03-7034-16, Data East/Sega/Stern #550-5036-06, Gottlieb #A-9394Y
Clear (not pictured) - Williams #03-7034-13, Data East/Sega/Stern #550-5036-01, Gottlieb #A-9394C