Agree with Wes. You need a solid support to stand on to get a proper stretch. That moving slant board does not seem to allow that, by the look of it. In this case, a picture is not worth a thousand words.
That one legged calf raise, that davie is doing, may be one of the best calf movements around. Apply a full stretch at the bottom and a fast and hard contraction at the very top. Really do not need a super duper calf machine. So get out that 4X6 block and start growing some calves. Good Luck.
