This is a Liliputi buckle carrier - I'm showing it with a newborn size demo doll (about 3kgs) and with a 3yo, 15kg Audrey. This is a smart and simple design - an internal harness for small babies that's adjustable with thick Velcro until baby is tall enough to sit in the base panel, and seat extenders that zip on to the panel (and thread on to the waist belt) to widen the seat for toddlers.
Here baby is seated in the internal harness. Feet can move freely either side, and baby is well positioned.
You can clearly see here that baby is not sitting in the full panel, but supported (like the Manduca) inside the panel by a harness. The height of the seat panel can be altered using hidden Velcro tabs.
Snaps secure baby in the insert panel.
That's some serious Velcro! You'll usually need to adjust your carrier fit when baby's clothing size changes ;)
Zip on/off seat extenders. They add a couple of inches either side to extend knee-to-knee support.
Hey presto, 3yo is well supported!
Chest strap easily adjusts for height and a snug fit in back carries. I really liked the dual adjusters on the shoulder straps and found they supported a very snug fit.
Because we like to take snacks on adventures...
You can see below that I have the shoulder straps almost - but not quite fully cinched - I am usually at the limit and hoping for more using a ssc in a back carry.
What's my verdict? Highly adjustable, with great longevity across your child's growth and development. It's been tried at several meets by people both more petite and generously proportioned to myself and it's quite popular. The harness for younger ages and the zip extenders for older are really the icing on the cake of a well-constructed, unfussy carrier. having tried several Liliputi products now (ssc, mama belt and Babywearing jacket) I can say I've been impressed by good design and excellent construction every time.