The Mamiya 25mm ID piece ring for eye cup is a vintage accessory designed for medium format cameras like the CDS Poro C220 and C330 finders. Made in Japan in the 1960s, this eyecup is compatible with Mamiya and Konica cameras, providing a secure fit for improved viewing. With a 1-month manufacturer warranty, this authentic Mamiya product ensures quality and reliability for photographers looking to enhance their viewing experience with a classic piece of camera gear.