Generally speaking, in a model number search we are looking for an alpha-numeric character in the first four characters (although some existing records do not follow this convention and thus will be hard to search). After that, the user can use wildcards (i.e. asterisk). Please note that the system cannot read model numbers cataloged in the Directory with parentheses. For example, some manufacturers have model numbers like (C,F,G)DE3921. The system will not take a search input of CDE3921 and know to pull that (C,F,G)DE3921 record.