The 4c is just like our other shellers in the way it adjusts to different size nuts. Turning the knob to the right closes it tighter(shells harder),and to the left opens it up for larger pecans (shells lighter). The difference in the shellers is size and strength. The 4c will actually shell a whole nut without pre cracking it. Most paper shell varieties do well this way. However the machine was orignally designed to be used in conjunction with a cracker. This method will produce the most halves.