4 inch square speaker. 4-5/8 inch diagonal hole to hole. 4 ohm 10 watt speaker used on many pinball machine backbox speaker assemblies including GottliebĀ® pinball speaker assemblies.
Depending on availability, speaker may be a slightly higher wattage and is considered an upgrade.
Reference:
29504 left speaker 4 ohm 10 watt 4 inch square29503 right speaker 4 ohm, 8 watt 2-1/2 inch squareCan substitute for 031-5004-00 speaker