Per the Rulebook they state:
"2.2. All participants are provided with standard Rubik’s speedcubes by the organisers. If they prefer, participants are also allowed to use their own customized cubes at the events."
"Their own customized cubes" does not specify if they can use any brand or the...
The North Iowa 2017 Rubik's cube competition has been announced! It will take place in Osage, IA, USA. You can register and find details at the website below. I hope to see you there!