HobbyKing multi rotor undercarriage is designed to fit mount tubes with a 12mm diameter and skid tubes with an 8mm diameter. The undercarriage is manufactured from tough but flexible plastic.
Mount Tube Spacing: 40mm
Mount Tube Hole Diameter: 12mm
Skid Tube Hole Diameter: 8mm
Please Note: Skid / mount tubes not included, please see the related items.
For heavy multicopters, I recommend getting some of these to add to the crab landing gear set, since each of these legs are quite flexible, if you have a heavy copter and have a rough landing, there is a high chance of snapping one of these in half. But having more (3-4 pairs vs. 2 pairs) it increases the rigidity and reduces the likelihood that it will break. Right now i run with 3 pairs on my HK Predator 650. It's not really necessary but with my 5200mah 4s battery and camera gimbal, it gets quite heavy.