http://www.rcmarket.org/5x13x4-f-pr-20468.html
i did just find those, dunno anything about the manufacturer, and they arent seald.....
so i dunno, also found these on horizon, i guess youd have to get 2 packs of 3 for an even set, they are made by rc screwz and there is no info on the bearings...
http://www.horizonhobby.com/Products...dID=RCZBF695ZZ