Description: The Seiko 6619A mechanism was introduced in 1963. It is also called the "Caliber 410" by the older naming scheme. The mechanism appeared as the "410" in 1963 and later as the "6619" in 1964.

It is a fairly simple self-winding mechanism, but considered quite efficient. The rotor drives with a ex-center changer the reduction wheel directly and so works in both direction. This mechanism is durable, requires minimal maintenance and is almost never idle. It is perfect for everyday workhorse watches which the Seiko-5 name specialized in. The balance assembly of this movement consists of a screwless Glucydur balance, which is regulated by a short regulator arm with a simple scale, and a moveable hairspring stud. It is located in two inhouse Diashock bearings. A traditional swiss-type pallet anchor escapement is used; the center second hand is driven directly.