Smoked Beef Jerky?

Was curious if anyone who smokes their own beef jerky had any advice on when you know it's ready.

I got a great deal on an electric smoker and have been smoking for about 6 hours now. I believe 5-6 hours minimum is ideal time depending on the amount you're smoking. Though I was wondering if there was a way to tell by examining the meat itself. Should it be very hard or flexable still is ok or what do you think?