The e-commerce giant has been granted two patents, CNBC reports — the first part of the patent for the “legs” of the drone, which help it land on uneven surfaces. The second part details propellers with robotic, adjustable wingtips.

Amazon has described how an “adjustable gear extension” could contract or extend, according to CNBC. From there, “distance determining elements” will help to determine how far from the ground the drone is. Sensors will be able to detect when the drone has hit the ground, and adjust if the drone lands unevenly or titled.

In the second part of the patent, Amazon (AMZN) described its ideas for robotic propellors, which will help the drone avoid some air resistance. The “winglets” on the propeller, which are adjustable and similar to those found on a plane, will help the drone counter the “pressure drag” in the air while it flies.

The patents were granted on Tuesday after they were initially filed in 2015, according to CNBC.