i have started to flight with a hk 450 without any previous knowledges, and after a crash i have decided to design my own landing skid, by the way, i have it design 1 cm taller to avoid touching the floor with the tail blade, with the original ones was so easy, and with this solution i have done no more. i recommend to change the original skid by a printed one, the reason is that in another crash with it, i have discovered that a printed skid takes a lot of energy when its broken, that means easier raparations and infinite new skids! note that there is another design for a 6mm pipe, the idea behind this one is that sometimes you broke only the skids and buy a new one from hobbyking without needing anthing more can be quite expensive, so, with these you only need a 6mm alu pipe from a hardware store.