Quick removable (training) prop guards for a JJRC H11D quadcopter. Modified from Busters quick release prop guard  http://www.thingiverse.com/thing:456722/#files

They are heavier than the factory ones which makes them great for slowing it down slightly and getting used to sensitive controls)  They have been field tested and survived being smashed into a steel tube fence

( caused by a strong, unexpected cross wind)

Use supports for best results.