Over the weekend I did a review on Retractable Landing Gear for the 3DR Iris. https://youtu.be/RidPy-lYev8 The parts used are made by IMP Concepts http://www.impconcepts.com/impstore The Electronic parts were ordered from Hobbyking.com
This is a very easy install as long as you Take Your Time and pay attention to detail. I also show some parts that work on the SOLO which extends the ground clearance and also some features that may enhance the GPS.
At the end of the review I put together a few clips of the retractable gear in action if you just want to skip the review.