These are a premium 608-2RS or 608RS or 608 RS removable rubber shield, grease lube, deep groove radial ball bearing. Examples of some common applications of this bearing are skateboards, in-line skates, quad skates, rolling walkers, 3-D printers, electric motors, even the back bearing in your alternator can be a 608 bearing. Grease is the preferred lubricant in most applications as grease generally stays in longer than oil in a bearing and therefore theoretically would require less maintenance. You will receive two sets of eight bearings for a total of 16. Usually ships in 24 hours!