Handling Large Object (LOB) Parameters in the CLR
Use SqlBytes and SqlChars to pass large object (LOB) binary type (varbinary(max)) and LOB character type (nvarchar(max)) parameters, respectively. These types allow streaming the LOB values from the database to the common language runtime (CLR) routine, instead of copying the entire value into managed space. SqlBinary and SqlString should be used only for small binary and character string values.
For an example of how to handle large objects, see the sample on CodePlex; see SQL Server Database Engine Samples for more information.