Heer mattresses always begin with 33 pounds of Swiss Toggenburger horsehair. Hair from the mane makes for medium firmness, while hair from the tail is much stronger. "Firmness is a very personal issue," says Heer. He's had several requests from clients to ship a mattress to their home just so they could test it out for a few nights. The quality of the filling also means his family's mattresses last 100 years — the horsehair just needs to be cleaned and re-covered every 15.