[jacquesm]

The very fastest fastballs are ~100 MPH. So 260 is not 'a little less than you can throw it', what will happen is that it will get dislodged on one corner, do a partial spin and then come flying at you (if it doesn't break up before that).

I'd really hate to be hit with anything at 260 MPH, especially not with a phone. Those things are hard!

[Retric]

That's why you want something that functions as a Shear pin. Basically, you don't want to have it attached in such a fashion that it could gain those kinds of speeds.