more Earth-bound purposes. These avenues eventually introduced versions of the inflating flexible Rogallo wing to the sport of skydiving. Irvin advertised a Hawk and Eagle model in 1967, but these were only available for a very limited time before they introduced the Irvin Delta II Parawing in 1968. This was the most produced and developed of the early Rogallo wing skydiving canopies. They were manufactured by three of Irvin's factories – in the U.S., Canada and the U.K. The Delta II had colored suspension lines to help guide the packing process, and also had a unique "Opening Shock Inhibitor" OSI strap that helped retard the high opening speeds and shocks. The packing volume of the canopy was slightly bigger than the then state-of-the-art Para-Commander. As one of the first types of gliding canopy, it received a considerable level of interest from jumpers. However, it developed a reputation for being unreliable, as it seemed prone to malfunctions on opening, possibly due to the unorthodox packing techniques for such a new design of canopy. However, when deployed successfully, the glide and performance was markedly better than a Para-Commander type canopy. The Delta II was available until 1975 and paved the way for other Rogallo Wing skydiving canopies, such as the Handbury Para-Dactyl. This was made in both single-keel and dual-keel versions as a main parachute in the mid to late 1970s, and also as a reserve parachute version known as a Safety-Dactyl. This was a US-made canopy and featured a sail-slider to reduce opening speeds and opening forces as is normal on a modern ram air canopy. A Russian Rogallo-Wing canopy known as a PZ-81 was available as late as 1995. The Rogallo wing canopy was superseded in the late 1970s by the ram-air canopies which had improved their reliability and performance, and reduced their packed volume, compared to all other gliding and non-gliding parachutes. Rogallo kites Rogallo wing kites control pitch with a bridle that sets the wing's angle of attack. A bridle made of string is usually a loop reaching from the front to the end of the center strut of the A-frame. The user ties knots (usually a girth hitch) in the bridle to set the angle of attack. Mass-produced rogallo kites use a bridle that's a triangle of plastic film, with one edge heat-sealed to the central strut. Steerable Rogallo kites usually have a pair of bridles setting