Clock suspension spring for German-made Hermle chain-wound and spring-wound mechanisms movements in modern day mantel, and wall clocks. 
movements series 131, 141, 151, 241, 261, 341, 351, 352, 451, 1051, 1151.030 The size is 5 /16” (8.0 mm.) wide x 11/16” (17.0 mm.) in length. 
Please call or email if you have any question or need another size .