Just a heads up caution for anyone owning or thinking of purchasing Master Airscrew propellers for the X-Star. Many of the propellers have loose hubs. These are the fixed-hub ones not the older ones with a separate nut. I've been using the Master Airscrews since the first day with my X-Star Premium, and I also have them on an X-380. Yesterday another X-Star flyer told me his props were loose at the hubs and rocked if you just gently lifted on the tips while attached to the motors. Even holding the prop in his hand and grabbing the top of the hub it could be rocked. While it does not appear to so loose that it's about to fly apart, this could be an accident in waiting. I have two sets of these props for my X-Star and one set on an X-380. I never noticed before but when I checked all of them last night I found that out of 12 propellers total, five of them have loose hubs. Strangely, the set on the X-380 were all fine... so far. One set I purchased for the X-Star, three props had loose hubs! Maybe between the two sets I can get one good one? I'm going to hang on to the good ones and trash all the others. I have flown many flights with these propellers and have never noticed anything wrong until I checked them last night. I guess it's not pronounced enough to really notice unless you purpously check each one. Beware of them if you already have them and maybe reconsider purchasing if you're thinking about getting them. Note: All three of my sets are for the X-Star. These props are compatable with the Autel, the X-380, and DJI even though there are ones specifically sold for the Phantom 3 series.