The Pierce 861 watch movement features a pin-lever escapement, a detached manual wind, and a barrel with a jewel bearing if it includes 25 jewels. It utilizes an indirect minute function with a hand friction clutch on the barrel, and a stem mechanism without a setting-lever spring. This movement is typically identified by the signature "158" and was predominantly used around 1970. Additionally, it offers several functions including automatic winding, sweep seconds, and a calendar with the ability to be set by +/-24 hours.