This is a set of vintage audio tubes made by the Dutch brand Philips. They are compatible with various types of vintage electronics, specifically those in the categories of Vintage Tubes & Tube Sockets, Vintage Parts & Accessories, Vintage Audio & Video, and Consumer Electronics. These tubes were produced as part of the PE 1/100 series, and are sold as a set of two. They are highly sought after by collectors and enthusiasts of vintage audio technology.