The Dovetail Plates are the heart of the Losmandy Secondary System. 0.5 inch x 4.0 inches x length of the tube assembly. Dovetail plates may be mounted to the top and bottom of tube assembly for mounting of all D series accessories, making it possible to use both sides of tube for equipment. The dovetail plates, like all accessories in the Losmandy line, are machined for lightness and rigidity from aluminum stock, then black anodized for a tough, corrosion free surface. Astrophysics dovetail plate for 4 inches, will fit top or bottom of their rings. Wt. 2 lbs. Length 13.5 inches HS 12.325/12.70, Ht. top of rings to top of dovetail plate 1.00 inches Thickness .5 inches