This is an arm guard for the iFlight XL range of quadcopter frames. It have design and fitted them for the XL7 arm which I believe is the same for XL5 and XL6 arms. you will need to mirror two of these when you print as the arms are asymmetrical. Printed using Sainsmart TPU, 0.2 mm layer height, 230 Degrees Celsius.
Sainsmart TPU 95A Shore Hardness