The Zenith Defy A3642 was introduced in 1969 as the brand’s first Defy, a tool watch built to withstand abuse. It has an octagonal stainless steel case of about 37 mm with a 14-sided bezel and a screw-down crown, and Zenith lists it as water resistant to 300 metres. The faceted case was chosen to protect the movement against shocks, which is where the Defy name came from.

The design belongs to the late-1960s wave of sports watches with a bold, faceted case that points forward to the 1970s. Zenith has described the A3642 as the origin of the whole Defy line, and the case geometry and bezel are what later models kept.

Original A3642s are scarce and collectors treat them as an under-appreciated corner of Zenith history, one that was rediscovered when the brand issued the Defy Revival A3642 in 2022 as a 250-piece limited edition that sold out quickly. The original is no longer produced; the Defy name continues as an active collection.