This flash is not backwards compatible with the Diana+ (item 550) because the Diana+ does not have the prong attachment point on the camera. It is intended for the Diana F+ (item 561).
• Descended from the original 1960s design, this retro-style beauty perfectly compliments the Diana F+ camera. The Diana-blue color scheme, silver faceplate, classic metal pin attachment, and glowing ready-light are all authentic hallmarks of the original. It's "Diana Plug" attaches directly to the camera and fully syncs the flash. An integrated color flash feature allows you to splash a burst of colored light at your subject - day or night - and a packet of plastic color gels come in the box. On top of that, a Diana Plug-to-Hotshoe adapter is included, which allows you to use the hi-powered and radiantly beautiful Diana Flash on any standard hotshoe camera like the LC-A+, Fisheye 2, Holga w/ hotshoe, many SLR's and DSLR's, and plenty of others!