1. Petzl Simba Full Body Harness
We love this harness. It comes up over the shoulders for greater support and is useful for younger kids that do not have defined hips for a waist to grab on to. Leg loops and shoulder straps are fully adjustable- according to Petzl, can be used up to 88 lbs. We adjust this harness down for our 18 month old and back up for our 3 and 5 yr. old with plenty of room to spare.
2. Petzl Alpine Harness
We do not yet own one of these, but our 5 yr. old has climbed in one a few times at the gym, and it is on our list to buy next. Alpine harnesses are light weight, usually less comfortable for adults, but fully adjustable. Meaning we could adjust all the loops down for our kids while a small adult would be able to wear it as well. This is a great harness if you want it to fit for a long time or a variety of people.