The Flange Bearing 14mm OD fits any of the channel and flat brackets with the common hole pattern having a center hole of 14mm. The inside diameter will fit any of the D-Shaft axels.
The Small Thrust Ball Bearing is used for vertical and axial loads to withstand heavy loads. These ball bearings have track grooves on the upper and lower track boards to reduce friction. Use these with structure for any hole where an axial load will be applied.