As Scar pointed out, " there are several ways to improperly install them". I tried some and wasn't happy with the results. I checked with other flyers at our field and there were more failures than successes. Now the only ones I use have the steel pin between the 2 plastic halves and I also use round tooth picks and epoxy to pin them. I have never had a failure and you can get them in different sizes to match the plane. [8D]