Weidmueller SD SK 13X125

SD SK 13X125 likely identifies a product, perhaps a tool or fastener.  "SD" probably denotes the brand, "SK" a model or series, "13" a size or dimension (possibly diameter or width), and "X125" a 125-unit length or other dimension (likely millimeters).  For precise product details, online searches, the SD brand website, or relevant catalogs/suppliers are recommended.