binary and varbinary (Transact-SQL)
Binary data types of either fixed length or variable length.
When n is not specified in a data definition or variable declaration statement, the default length is 1. When nis not specified with the CAST function, the default length is 30.
Use binary when the sizes of the column data entries are consistent.
Use varbinary when the sizes of the column data entries vary considerably.
Use varbinary(max) when the column data entries exceed 8,000 bytes.