What are the reward levels for the Arena?

Currently between each reward level there only seems to be a bar saying how far along you have progressed. And how far till the next reward, for example, between challenger 1 and challenger 2.

What are the gaps between each one?

Solution 1:

Based on my knowledge of the arena, the intervals between ranks are based on player ranks and their amount of arena points, I do not know any solid numbers due to the fact Netherrealm hasn't shown any sort of numbers for the ranks. The main reason I believe the ranks are based off of player points and not set values is because after a short period of time not running arena I noticed my rank dropped two ranks while I wasn't fighting.

If Netherrealm ever releases any sort of solid numbers on what ranks represent on the leaderboard I will update this answer to reflect that.