Seiko uses their own SPRON alloy for in-house spring production.
Nivarox-FAR is the name of the manufacturer of the corresponding balance springs and assortments. It is part of Swatch Group. Although Nivarox-FAR produces most balance springs used in Swiss and other European watches, a few companies produce their own springs using the alloy. Rolex, Parmigiani, F. P. Journe, and A. Lange & Söhne all have the capability to produce their own Nivarox springs. Thanks to their Richemont connection with Lange, Jaeger-LeCoultre also produces springs from Lange material.