The Ally Dog Pro Ultra Sonic Disc. Caledonia Fly Company has found a disc that is a step up from your normal Conehead designed patterns. The Pro Ultra Sonic disc’s designed by Morten from Pro Sportfisher are the world’s first brass discs with holes. The Pro Ultra Disc’s are designed to optimise wing movement. The disc is an outstanding piece of engineering as it maintains the capability to create a vortex behind the disc to cause our materials to dance around behind the disc and not letting them collapse in the faster currents of your river. Also these are very easy to cast off the water due to the vented holes.