The grow with me woombie is a swaddle + wearable blanket that covers your growing baby from 0-9 mos. with a bonus extended length to reach up to 18 months! features of grow with me woombie: converts from swaddle to sleeping bag covers all 5 stages of sleep birth - 18 months our signature bebeflextm fabric for the perfect swaddling effect baby milestones - no problem allows for growth spurts rolling arms free transitioning stage 1: swaddle 0-3 months/ 2.2 - 6 kg, for babies 50cm+ long, fully zipped benefits: stretchy fabric, ergonomic design, mimics womb, promotes self soothing stage 2: swaddle + 2-4 months/ 5.5 - 7.25 kg, for babies 56cm+ long, unzip 2/3 way benefits: "in-between" size, covers growth spurts, unzip to bottom opposite corner stage 3: expanded swaddle 3-6 months/ 6 - 8.5 kg, for babies 60cm+ long, fully unzipped benefits: converts to new size, extra hip space, mimics the womb, prepares for new milestones stage 4: transitioning 6-9 months/ 9 - 11.5 kg, for babies 60cm+ long, arms free benefits: arms free sleep, easy transitioning, extra length as needed, promotes self soothing stage 5: sleeping bag 9 - 18 months/ 9+ kg, for babies 68cm - 84cm long, fully unzipped benefits: super length, room to grow, promotes self soothing please note that the happy elephant is the woombie grow with me air design which has a organic mesh lower allows increased airflow while swaddling during warm months