I bought the smoker box from the local fireplace and BBQ shop for $10. It's nice and heavy cast iron - should be durable. The instructions printed on its wrapper were clear and simple. I filled it with dry hickory chips, put it on the grill of my gas grill, put the grill on high and in 15 minutes there was a good amount of smoke. Then I turned the heat down and put some ribs in a rack over a water pan which sat on the half of the grill I had covered with heavy aluminum foil. Several hours and a couple of water refills later the ribs were done. They tasted great and we saw a well-defined pink smoke ring in the meat.
An added bonus was that when the cast iron cooled and the kid was removed, the wood chips had turned to charcoal and the inside of the box looked like a Louise Nevelson sculpture. Really kind of beautiful.
In the past I've used foil packets of wood chips. This box seems to work better, with more prolonged smoke. I read a suggestion to use two, one dry and the other with soaked chips, with the idea that the wet chips will take longer to start smoking, and between them and the dry chips there'll be a longer period of smoke.
Well worth the $10 it cost me and would have been worth $15.