Anyone heard of BumberChutes training pants?

[beyoung]

I just picked up 3 pair of these (brand new in their packages) for $1 each at the local Goodwill store. They look pretty vintage but I'm wondering if anyone has tried them before? They look like regular underwear but inside they have a waterproof lined (maybe PUL???) pouch with elasticised edges that you're supposed to put a disposable insert into. Each package did come with one disposable insert but I figure I can use a prefold or some other reusable insert instead. The concept looks neat to me and since my little guy is starting to show interest in potty-learning, I figured at that price, I might as well give them a try.