While all stretchy wrap are long pieces of stretchy material, individual brands can be quite different to one another. And one of the most striking differences can be in HOW these wraps stretch. In particular there are two main flavours - One-way and Two-way stretchy wrap. But what does this mean? What is the difference?
Simply put, a one-way stretchy wrap is one that stretches in ONE direction only (or stretches much much more in one direction than the other). Generally these wraps stretch only in the vertical direction (along the width of the wrap). While a two-way stretchy wrap stretches in two directions - both along the width and the length of the wrap.
You can see this for yourself here;
So what are the pros and cons of each type?
Two-way stretchy wraps are easier to pre-tie and then pop your baby in because they are stretchier and because they stretch evenly, which means they stretch in a way that feels more intuitive - easier for your brain to understand and predict. So it's very easy to put the sling on and get it tight enough that it will support baby once they are in but still have enough space to stretch it out to put baby in easily. Conversely, One-way stretchy wraps are much harder to pre-tie because they don't stretch evenly. That uneven stretch means it is often quite hard to tie them tight enough that they will support baby once in and still have space to get them in easily. The window between too tight and too loose is just much smaller. Consequently, I often think of pre-tying a one way stretchy wrap as being a bit like finding the right setting on a tempermental old toaster where there is just about 2mm between still bread and completely burnt. The window on a two way stretchy wrap is simply much wider and so it is much easier for a new sleep deprived parent to learn.
It is worth noting that you can tie using methods other than the pre-tie method, and this can work a lot better for one-ways. But often the manuals only show the pre-tied method so parents don't realise this is possible and often the whole reason they bought a stretchy wrap in the first place was because they wanted the convenience and ease of being able to pre-tie first and then pop baby in and out as needed.
On the flip side in general one way stretchy wraps are more supportive of bigger babies. The reason for this simply being because they are less stretchy they don't get stretched out as much as baby grows, while a more stretchy two way will definitely start to feel more "bouncy" and less supportive as baby gets heavier between 4-6 months. But often parents are moving on around this point anyway as babies tend to grow out of either type stretchy wrap developmentally rather than physically as they go through the huge developmental leap that happens somewhere between 3 and 4 months. So being less supportive isn't a huge con, but it is worth noting if you have reason to believe your more likely to be using a stretchy wrap for longer (i.e. developmental delay or other special consideration).
Which brands are one-ways or two-ways?
Well known one-way stretchy brands include; Moby, Ama, Liberty, Funki Flamingo, Free-Rider, Manduca, ByKay and most the cheap stretchy wrap brands found on Amazon
For more ways in which stretchy wraps differ and a huge table comparing 16 different brands please do check out this article.