Reserve parachutes are packed and deployed somewhat differently. They are also designed more conservatively, favouring reliability over responsiveness and are built and tested to more exacting standards, making them more reliable than main parachutes. Regulated inspection intervals, coupled with significantly less use contributes to reliability as wear on some components can adversely affect reliability. The primary safety advantage of a reserve parachute comes from the probability of an unlikely main malfunction being multiplied by the even less likely probability of a reserve malfunction. This yields an even smaller probability of a double malfunction, although there is also a small possibility that a malfunctioning main parachute cannot be released and thus interfere with the reserve parachute. In the United States, the 2017 average fatality rate is recorded to be 1 in 133,571 jumps.