Manufacturer recommended age, ‎12 months - 6 years. But some parents introduce simplest climbing structures (small Pikler triangle/small arch) already starting from 10 months old or when baby is learning to crawl/stand (detailed explanation below). 1.5-3 years actually is a climbing stage, though use of climbing toys also surely depends on the very child, if he is active and enjoy climbing-like activities in general. Also climbing frames can be used for more than just climbing, for example, as a fort or flipped arch with a blanket on can be enjoyed as a rocker. 

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Emmi Pikler, the designer of the Pikler triangle, noticed that babies with the opportunity will begin to climb when they're ready - and it’s often much sooner than you might think!  

The simplest climbing structures (for example, small Pikler triangle) parents mostly introduce around 6-8 months, when babies are learning to sit and will be ready to pull up to standing soon. Most people associate climbing with older children, but even the pulling and lifting of feet onto the first rung is the first step in developing core strength. Big climbing triangle is relevant until 5-6 years old!

When your child becomes a toddler the Pikler triangle benefits kick in as they teach themselves how to climb, descend, and balance, they’ll start to push their abilities and boost their motor skills and confidence. 

In preschool ages, advanced play arrives. You can then start to combine your Pikler triangle with other climbing playsets to create obstacle courses and imaginary worlds!