Here's a search link on ebay
https://www.ebay.com/sch/Business-In...+gasket+rubber
I've worked with the two piece type. There is a a speciality tool I borrowed to install the locking strip. Made a difficult job easier.
The one piece looks like it works on the same principle but can be tucked in a little easier.
Good luck and keep the small children away as you will probably be using the "universal adjective" frequently
