The infant monitor "Baby Arm" can be used from 0 months old and provides peace of mind with its monitoring features. - Brand: BabySmile - Model Name: Baby Arm - Function: Infant Monitor - Target Age: From 0 months old - Included Items: Instruction manual - Color: White I purchased this on Mercari and used it for about a month. It worked without any problems. Batteries are included. Thank you for looking.