The TRI507745 is a Heavy Duty Open Type . Single Row Machined Needle Roller Bearing with an Inner Ring. The Inner Ring is separable from the Cage and Outer Ring . while the Outer Ring is fixed to the Cage and has an oil groove and an oil hole. Bearings with an Inner Ring are used when the shaft being used isn't heat-treated and finished by grinding. In caged Needle Roller Bearings like this one . the Needles are precisely guided by the Cage to achieve ideal load distribution. These Bearings are designed for high load carrying capacity in radially compact arrangements and are used in most general purpose applications. The Bearing's dimensions are 50x77x45mm.