The Soprod “Alternance 10” (also called the A-10, A10, and A10-2) is a Swiss Made movement based on the Seiko 4L25 design but produced in Switzerland under license. It is an advanced, slim automatic movement with modern technology and is not a clone of the ETA 2892A2 with which it competes.
The A10 is instantly recognizable thanks to its counter-clockwise balance cock and automatic winding rotor mounted with three screws and seven ball bearings.
Although a Japanese design, it includes many signature Swiss features, including Incabloc Double-Cone shock absorbers and an oscillating pinion automatic winding switcher. It is exactly the same size as the ETA 2892A2, with the same locations for dial feet, crown, hands, and date window. This makes it a drop-in replacement when that movement is unavailable.
Seiko Instruments first designed their 4L25 to create an ETA 2892A2 competitor for the Swiss OEM market. Soprod announced their Swiss Made version, Cal. A-10, in 2004 and began offering it to Swiss watch makers. The company was not explicit about the design source of the movement. In 2007, Soprod was acquired by Peace Mark of Hong Kong for the company’s quartz movement operations in China, and the Swiss mechanical operations were sold to Festina Group the following year. Seiko introduced their own 4L25-powered Brightz and Credor models and Soprod continued to produce the A-10 and later the A10-2.