UR65 (UK/US) is a really great mini quad ... except is flight time!
Here is an adapter to be able to put 450mah batteries (a bit more 5 minutes of flight time) , and as a bonus allows to fix the antenna ;)
For installation simply clip the bracket into the chassis hole.
UPDATE 10/28/2018 : Ease of interlocking; USB accessibility ; battery cage option
Help me replace filament and make updates, thank to tip me: Here