Boot Rubber Seal - Mk IV

Does anyone know the type of boot lid rubber seal used on the Mk IV?
The very tattered and hardened one on my car is an ‘L’ section laid on its back, with the foot of the L having a return of the same size to wrap the upstand flange of the body channel.
The spares catalogue lists two, a ‘Sorbo’ and a rubber seal. What are these parts, what do they look like, and how do they fit?
Is a suitable correct style of replacement seal available?