After years of testing, Minolta offered its first durable, poly-carbonate lens mount in 1994 with the Dynax 400si. It has since continued its use with the Dynax 300si and Dynax 505si, 505si super, 404si, 303si, Dynax 4, 3 and Dynax 50. The poly-carbonate mount is proven to have excellent durability under the average use encountered by owners of these cameras.