Last week, Southwest Airlines announced an end to its long-time policy of two-free checked bags. Frontier officials say customer response will help determine if its free service will become permanent. The promotion is good for Frontier flights departing between May 28 and August 18. You'll need to use the promo code "Free Bag" to get the perk.

"Breaking up with your old airline? We’re here for you!" said Frontier Airlines. The Denver-based airline said a new free bag policy could become permanent.

Frontier Airlines launched a promotion that includes free checked bags, taking aim at rival carrier Southwest, which reversed its long-standing policy.