Easy to put on, and it stays put.

Let's first remind ourselves that this item is made by Kelty, one of the premier manufacturers of outdoor gear. If they put their name on it, surely it is a quality item - and it is.I have a 73lb lab/Weimaraner mix (with identical build to a typical Weim) and the medium fits her perfectly, albeit on the snugger side of the adjustment range. I read other reviews and they complain about difficulty in preventing the pack from sliding over their head on downhills or when they drop their head, but I've yet to have that problem. We have hiked several times and been on OHV excursions several others, where she has carried her own supplies and some of my own, as well.The harness system on the Kelty is one of the better designs out there, with the Y-yolk and chest pad for optimum comfort and security. The pack slips on easy, and is buckled in at two points under the chest.Overall, an excellent product (durable, waterproof, comfortable, and practical) from the venerable brand Kelty, at a very competitive price. Strongly recommended.