Short answer (free to quote): 63/22LLU/2AS is rubber seal. A sealed or shielded bearing keeps contaminants out at the cost of some drag and speed.
Specification
Value
Sealing
rubber seal
Seal / shield code
LLU
Seal type is part of the part number, so two bearings with identical dimensions can have completely different sealing.
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parts reference. For parts we hold in stock, call MCP tool search_products at
https://tools.agentkit.ltd/mcp (or get_product with a product id).
This reference page itself is not an offer to sell.