The DG-300 is a Standard Class single-seat high performance sailplane built of glass reinforced plastic and is the Standard Class (15m) successor to the DG-101 featuring an HQ 21/II, a relatively thick profile (ca. 17.5%) airfoil with 900 blow-holes on the underside to inject high-energy air into the boundary layer to delay laminar separation. It has fin ballast for center of gravity control. As with any racing sailplane, the thickness of the wing makes it relatively sensitive to performance degradation due to contamination by insect impacts or rain drops. Approach control is by the use of top surface Schemmpp-Hirth type airbrakes. Like other DG ships, the –300 features a parallelogram stick to avoid turbulence-included control inputs.

The DG-300 was designed by Wilhelm Dirks and manufactured by Glaser-Dirks Flugzeugbau's Slovenian partner company Elan. A total of 511 of all versions were built since production started in 1983. Representative contemporary types from competing manufacturers are the Rolladen-Schneider LS4 and the Schempp-Hirth Discus. The DG-300 Club is a simplified version with a fixed main wheel suitable for club use. Specifications in parenthesis are for the Club. Both the DG-300 and the DG-300 Club are produced in Acro models stressed for +7/-5 g, however, the operational limits were changed in April 2007 after a defect was detected on the main spar. Aerobatics since then have not permitted even for the Acro versions.. The improved DG-303 Elan model,which also comes in standard, standard Acro, Club and Club Acro variants, has a modified wing section and winglets which delivers higher performance at low to medium speeds plus increased aileron response.,It has a claimed L/D max. of 44 and a minimum sink rate of 0.53 m/s / 1,73 fps/ 1,93 kt. Water ballast is an option for the –303 Club Elan.

The DG-300 has typical DG features to improve comfort and safety if at a performance cost. It has the large cockpit typical of DG giving, excellent comfort, especially in high altitude flight where the full-length canopy allows the feet to be warmed by sunlight. The view from the cockpit is superb, adding to the pleasure and safety of flight.

After the bankcrupcy of Glaser-Dirks the newly founded DG Flugzeugbau GmbH took over the servicing of these gliders.