The Autojector I used totally enclosed the loaded syringe, with a button on the side. I could reach my arms and backside, and just press the button one handed. The needle was quickly inserted, AND plunger also pushed in from the spring loaded release. Just had to count to 5 to make sure insulin was delivered before pulling away.
I think I had Autojector I or II. It was black and grey, with a red button. It had 2 parts that screwed together, after putting in the loaded syringe. And multiple tips that screwed on the end to adapt for different needle length.