<https://community.ultimaker.com/topic/9159-what-fans-to-install-on-umo/#comment-103297>
<http://schema.org/text>
"The original UM used a 12v 50mm fan. If the UMO uses a different fan it should have a sticker on it that says what voltage it is, and the edge measurement of the fan should be close to 50mm or 40mm for a fan of those sizes. The measurement is actually the screw hole center to center measurement. The UM2 uses 40mm fans I believe. \n  "
<https://community.ultimaker.com/topic/9159-what-fans-to-install-on-umo/?tab=comments#comment-103299>