Instead of
MultiSelect.CommandText = "Select SKU, Manufacture, Name, Price From Products WHERE SKU =" + SKUS[i];
try
MultiSelect.CommandText = "Select SKU, Manufacture, Name, Price From Products WHERE SKU = @SKUS";
MultiSelect.Parameters.Clear();
MultiSelect.Parameters.AddWithValue("@SKUS", SKUS[i]);
Ensure SKUS[i] is the same object type as the field SKU (ie numeric or string etc).
Also move what is not necessary out of the loop. (open, commandtext is the same for all interations and it will be open for the second loop so in the loop is only the parameters clearing/ setting and the execute.