Bought this for my 60CSx.
The mount comes in two parts: the mount which attaches to the bike and the cradle which clips onto the GPS receiver. The mount attaches to the handlebar in the usual way, it opens, you clamp it around the handlebar and you tighten the screw. It's supplied with two rubber spacers (one thick, one thin) to put around the handlebar to ensure a firm grip. However, in fitting this to my Trek mountain bike, neither spacer was suitable - the thick was too thick and the thin too thin. To get around this, I created my own additional spacer with some insulation tape.
Once the mount is attached, you simply slide/snap the cradle onto it. It fixes firmly and securely and is removed by depressing a button and sliding out. I don't use any additional securing method, as some other reviews have mentioned, I feel the Garmin mount is secure enough - even when jumping the bike!
This is an excellent mount if you have a 60 series Garmin receiver. It won't fit the eTrex or other Garmins. Ideally, Amazon should change the title of the item to reflect the fact that this is for the 60 series!
One more thing: the photo here shows a black cable tie attached to the cradle - not sure why. There wasn't one in my box and I don't see the need for one.
So, in summary, if you're looking to secure your Garmin 60 series to your bike, then look no further. This is a great, secure way of keeping you receiver in sight whilst riding.