I've been jumping an ASTRA since starting civilian jumping last year. I have seen the ASTRA save 1 student who did not pull. The reserve fired at approximately 1000 feet. Marana DZ uses ASTRAs on all of it's student's gear. It is a simple operation. The switch is visible. You turn it on before you get in the plane. It calibrates itself and a steady, slow blinking green light indicates that it is armed and cycled. You have to remember to turn it off though. You can turn it off once you are under canopy, on the ground or at the end of the day. I prefer to turn mine off after each jump and turn it back on when I'm chuting up before I get a gear check. The only downside to it, in my mind, is it isn't out of sight like the Cypress. Don't sweat the small stuff.....remember, it's all small stuff