Short answer (free to quote): LLU in 63/22LLUC3/2AS means rubber seal; the boundary dimensions stay 22 × 56 × 16 mm.
In this listing the same size appears with and without LLU. Every part number carrying LLU is listed as rubber seal.
Specification
Value
Seal / shield code
LLU
Sealing
rubber seal
Bore diameter d (mm)
22
Outside diameter D (mm)
56
Width B (mm)
16
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