FYH Circular Housing Bearing with Boss Cylindrical Bore (with Set Screw)...Use Bearing UC2 (X) Series UCFC2 (X) Normal, L3 Triple Seal, C, D (FC, FD) With Steel Cover or Cast Iron Cover 1) Tapered hole (with fasteners)...Use bearings UK2 (X) series UKFC2 (X) normal product, L3 triple seal product, C, D (FC, FD) with steel cover or cast iron cover 1). It is a bearing with a block which is composed of a ball bearing for the assembly and a bearing housing with a circular seat mounting surface and a boss. When installing the bearing housing on the machine body, first insert the boss into the mounting hole on the machine body, and then use 4 bolts. The bearing housing can be mounted in the correct position by fitting the boss into the mounting hole on the machine body. Main applications: Rotating drums, rotating rollers, applications requiring high installation accuracy, etc. FYH with steel plate round seat bearing cylindrical hole (with set screw)...Using the bearing SB2 series SBPF2 lightweight type assembly ball bearing and press-processed steel plate bearing housing made of a combination of light-weight round seat for light load bearing. When installing the bearing housing to the machine body, use 3 bolts. Main use: light conveyor, light load and low speed use, etc. FYH with steel plate rhombus bearing cylindrical hole (with set screw)...Using the bearing SB2 series SBPFL2 lightweight type assembly ball bearing and stamped steel plate bearing housing made of light-weight diamond-shaped bearing for light load combined . The installation space is reduced compared to steel plate round housing bearings. When installing the bearing housing to the machine body, use 2 bolts. Main use: light conveyor, light load and low speed use, etc.