I wanted an auto feed for my K3800 but I did not want to spend $600 dollars for an auto feed for the K3800 so I bought the Auto feed on E-bay for $160 or $180 delivered to my door. I was able to make it work by bolting a 2" x 7" long piece off angel iron to the bottom of the aluminum frame that holds the drum. It was to low so I used a piece of Unistrut and raised it up 1/4"o so and aligned it with the drum. Now I have an auto feed on my K3800, it seems a little cheap and unusual. I am used to auto feeds with some adjustment for cable. This works for 1/2" and 3/8" cable with no adjustment. As I pull down on the lever from neutral something slides back on the auto feed and the auto feed compressed down on the cable and allows it to go into the drain. I haven't used it on a drain yet but it looks like you put your foot on the foot air switch a hand on the self feed and the remaining hand to feed the cable. It doesn't look like the auto feed works unless your hand is on it? Kind of unusual to me for a drum machine with auto feed? What do you guys think. Who used the K400 with auto feed? thanks for the input.