Films

Can you please explain what is 'films' here?

The resulting design is sealed against the ingress of dust, rain, and sweat. That allows you to wear Kailo inside of the pool, in the shower, or otherwise out in wet areas. You just want to keep it clear of cleaning chemicals, especially ones that aren’t supposed to be used with films and plastics. You can clean a Kailo patch using ordinary mild soaps and water, just avoid alcohol-based cleaners and you should be good.