The black look 608 Full Ceramic Full complement Silicon nitride Si3N4 Ball Bearing 8mm Bore, 22mm diameter and 7mm wide. Full complement means that there is no balls cage (aka balls retainer), making the bearing slower, but gets the benefits of taking high temperature up to 1000F degrees, you will have to find lubricant that takes that temperature, check with your grease lubricant manufacturer.
These bearings are made of Silicon Nitride Si3N4 , No-Rust, Non-Magnetic and Non-Conductive making it perfect for any food, pharmaceutical applications.
The funny thing is that this item can fit in a scooter :) and yes, these bearings can fit in any skate application like skateboards, inline skate, roller hockey, roller blades and inline blades, but who would pay almost $500 for 8 skateboard or longboard bearings or $1000 for 16 skate bearings?. Also, they wouldn't be good if you plan to jump stairs or apply any dynamic loads on them, it would be perfect if 1) You are a rich person 2) You are a cruiser kind-of-skater 3) You needed the lowest friction bearings ever.
Buy them online at http://www.vxb.com/page/bearings/PROD/CeramicBallBearings/Kit7900 the price is for one bearing, you will need 4 for a scooter (who would use those on scooters) 8 of them for any penny, nickel, skateboard or longboard, and 16 of them for the roller hockey, inline skate or roller blades.
However, even if you are rich, get real and buy affordable bearings with high quality, for skateboards, I would buy this set of 8 hybrid ceramic bearings, here is how they look and click on this link to visit the original site: http://www.vxb.com/page/bearings/PROD/Kit7809