Kettlebells are a fantastic, durable and useful fitness tool. They have been around for a few hundred years and have been used by everyone from beginners to special forces for training. The two main kinds of kettlebells are traditional and competition. As you can see in the video, the competition kettlebells are always the same size, no matter the weight. While the traditional kettlebells go up in size as the weight goes up. Both are great and will be fine to use in the Mountain Fitness Training program.
Personally, I like the traditional kettlebells from Rep Fitness. Below are links to get the two brands I most recommend. It would be beneficial to have more than one kettlebell, allowing for a heavier bell for swings and a lighter one for presses. If you are only able to get one bell, opt for lower weight. You can always master this kettlebell and move up from there!