— inflatable and self-inflating articles (see "Type") having more than one valve. Features of such products depend on the number of seats. So, in single models, two valves are usually installed — inlet and outlet, each with the corresponding functional features; such mats are significantly superior to single-valve ones in terms of convenience and speed of inflation and deflation. But in double products, where each half is usually inflated separately, for such increased convenience, four valves are needed — two for each compartment; such models are also found, although quite rarely.
