Works best: From birth to 4 years, depending on toddler height/leg length
Options: parent facing, back carry.
Straps: All buckles, crossable or ruck style shoulder straps
Some people like this for:
Newborns(No insert!) , sharing with another adult. Adjustable seat and body panel. Simple design.
Some people don't like this:
Buckles/webbing may put pressure on adults breast tissue in the early days. Thick padded shoulder straps can feel bulky.
Instructions can be found here: https://uk-boba.com/pages/boba-x-instructions
Youtube videos here: https://youtu.be/uEIj-SFXg-k