Pretty darned tough!
The pump itself is standing up to day to day wear and tear just fine, including being bashed against the odd door frame. There are no marks on it at all and it seems pretty water (well sweat) resistant and copes with much bouncing around playing Badminton and when out on a bike.
I'd suspected that the infusion set (the tube from pump to cannula) would be a bit fragile, so I set about trying to break one when I changed a set. I can tell you now, that despite looking thin & fragile, it's anything but fragile. I tried to pull the tube out of the end that screws onto the pump end, but although it stretched a bit, it would not come back, Trying to snap the tube didn't work either, it just stretched a bit.
|Two tubes in one|
Next I cut it in half, which demonstrated how tough it was as it required a fair bit more effort than I was expecting. After cutting, I then cut a slit down the tube (somewhat tricky with such a thin tube), which revealed another tube within.
So, the verdict - you win' gonna be snapping or pulling the infusion tube out of anything. It's plenty strong enough to get caught on something without issue and the pump itself will quite happily swing around, dangling on the end of the tube. The weakest point if the cannula itself that can get pulled out, but that's not such a bad thing!