I had a cube climber and a triangular shaped one. They each had a slide down and it was easy to be right there to monitor the little ones. They could crawl under the triangle one, too. The cube climber was one of the smaller ones and was perfect for under 2s. Just the right height for them to climb, stand and slide. The triangle one was great for my over 2s... basically I figured as soon as they were coordinated enough to climb onto it, they were ready for it. They spent a lot of time on both of these and they didn't take up much backyard space at all.