Arms open to convert from the Original Woombie swaddle sleep sack to an arms-free sleep sack when the time arises to transition the baby. Swaddle your baby safely and effectively with The Woombie ... designed to ease your mind and comfort your baby so you may both achieve a better nights sleep. The Woombie is the one natural & safe way to swaddle your baby, mimicking the ability to stretch extremities as in the womb, yet gently comforting & stopping startling issues and more!! Recommended by: Doctors, Nurses, Doulas, Physical Therapists & countless Moms & Dads