The big three models of flange bearings

Since flange bearing are designed to increase  accuracy of position, there are thousands and hundreds models availability.Each designed for applicability of particular ball bearing functions and requirements.
When selecting a high speed bearing, the dimensions should suit the diameter of the shaft, and they are thus available in a myriad of sizes. The largest differentiating factor between flange bearings is the number of bolts (mounting holes) on the mechanism.

Double-bolt flanges
These flanges are available either in a wing-shape or in a diamond shape, which have two mounting holes, (usually elongated for simple, user-friendly adjustment). They are engineered to be repositioned and aligned for the best fit of shaft
Three-bolt flanges,these flanges are round, which have three equidistant mounting holes.
They are engineered to be repositioned and aligned for the best fit of shaft.