There are a few properties of such hardware that can help confirm the correct replacement parts, assuming you can't do a positive serial number search, but sometimes it still comes down to a bit of a gamble. Here's how I'd work the problem.
Establish your door type (model or series) and year of manufacture. Some parts lookup systems use year to determine which generation of a similar product you have.
Verify swing, size, and other aspects of your door. There may be opposing, symmetrical options for each swing, for example.
Look for any dimensions provided. Sometimes hardware is offered in several sizes, but it looks almost identical in photos without a size reference. Actual dimensions are a very good corroborator.
As a final check, scrutinize the details of the part. Every hole, corner, connection, and shape should match (unless your part has a newer version, which does complicate things). If you spot differences, consider whether the position and function appear to be compatible.
If all those things seem to align with the universe, you're probably ok. Check return policy (or resale potential) if you're still in doubt. Then cross your fingers and click the button.
