You increase the Speed that you can move while Sneaking by +5 feet per rank of this feat, up to your maximum movement speed with a given form of movement (i.e. Fly, Swim, Climb, etc.).
You gain a +1 Bonus to Stealth checks to Sneak for each rank of this feat you have.
You can have a maximum number of ranks in this feat equal to the number of Proficiency Boosts you have in Stealth.