What are Xtra Boosts? Members of FLX Rewards can add Xtra Boosts their entry and improve their chances to win exclusive sneaker releases. Related articles How many Xtra Boosts can I apply to each release? How do I get Xtra Boosts? What are Xtra Boosts? When can I add Xtra Boosts to my entry? I have already submitted my entry. How do I add Xtra Boosts?