> For the complete documentation index, see [llms.txt](https://eako-capital.gitbook.io/eako-user-guide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://eako-capital.gitbook.io/eako-user-guide/variations-on-barrier-options/partial-double-knock-out.md).

# Partial Double Knock-Out

A Partial Double Knock-Out is Vanilla option that ceases to exist (is "knocked-out") if the underlying spot reaches either one of two fixed barriers within a predetermined period during the life of the option, i.e., the risk of the option being knocked-out is confined to a "sub-period" only, not the whole maturity period.

This may also before be referred to as a WIndow Double Knock-Out, where the barrier is observed during a "start" and "end" window period.