There are numerous types available, and many have no inner rings
There are numerous types available, and many have no inner rings. The drawn-cup type has a pressed steel outer ring and the precision (solid) type has a machined outer ring. There are also cage-and-roller assemblies without rings. Most bearings have pressed steel cages, but some are without cages.
Drawn cup needle roller bearings have a drawn outer shell serving as a raceway for the rollers and are installed with a press fit in the housing. They are ideal for many of the following applications: transmissions, transfer cases, engines, valve trains, steering and braking systems, axle supports, outboard engines, textile industry, power tools, copiers, fax machines, paper-moving equipment, and appliances.