A
pyrotechnic fastener (also called an
explosive bolt, or
pyro, within context) is a
fastener, usually a nut or bolt, that incorporates a
pyrotechnic charge that can be initiated remotely. One or more explosive charges embedded within the bolt are typically activated by an
electric current, and the charge breaks the bolt into two or more pieces. The bolt is typically scored around its
circumference at the point(s) where the severance should occur. Such bolts are often used in space applications to ensure separation between rocket stages, because they are lighter and much more reliable than mechanical
latches.