The Power-Pak 445 (PP445) by Universal (a division of Nautilus) is an adjustable dumbbell set that allows you to adjust the weight of the dumbbells from 4 to 45 pounds in 5lb increments. Traditional dumbbells are expensive. They typically sell for around $1 per pound, and take up a lot of room. If you're at a gym this isn't a problem. If you're working out from home, it is a real pain to store 7 or 8 sets of dumbbells, and bring them out and put them away after a workout. I am a big fan of adjustable dumbbell sets. Not only do you usually save money, but you get a lot more variety which makes your workouts faster and more efficient, and prevent clutter in your house. The only disadvantage to them, is that they're bigger than standard dumbbells, which can limit your range of motion in some exercises, and you can't drop them or be as rough with them as regular weights.
Below are the major brands of adjustable dumbbells that Amazon sells in the 50 pound range. I've listed them based on a combination of popularity and rating based on what I think are the best to least best, with the Bowflex SelectTechs (which I'll refer to as BST) at the top. I currently use the BST and I think it is the best adjustable dumbbell option right now, so the rest of my review will compare the PP445 to them.
1. Bowflex SelectTech 552 Adjustable Dumbbells (Pair) 5 to 52.5 lbs in 2.5 pound increments
2. PowerBlock Classic Adjustable Dumbbell Set 5 to 45 lbs in 5 pound increments
3. Ironmaster 75 lb Quick Lock Adjustable Dumbbell System - 5 to 75 lbs in 2 1/2 pound increments, includes stand
4. XMark Fitness Adjustable Dumbbell 5-50 lbs 5 to 50 lbs in 10 pound increments
5. Performance Fitness Systems TB560 5 to 60-Pound Adjustable Dumbbells with Stand 5 to 60 lbs in 2.5-pound increments, includes stand
6. Bayou Fitness Adjustable Dumbbell(50 -Pounds) 10 to 50 lbs in 5 pound increments
There are two features right away about the PP445s that I like. The first is that they come with a stand. For the dumbbells above that don't come with a stand, expect to pay an extra $100 - $150 for one. It's not a requirement, as they all contain some type of base that they fit into, but you don't want to have to pick up heavy weights off of the ground, which can throw your back out or tire you out before you even start the set. Of course the disadvantage to this is that a stand takes up dedicated space in your house, as opposed to just putting the weights in the corner or under a bed. But if you do have the space for it, I recommend getting one. The second feature, is that these weights have a smooth weight selection system that makes it very quick and easy to adjust the weights to different levels. My Bowflex SelectTechs work pretty well, but every once in awhile they will catch and not lock in on a certain weight. The 445s don't seem to have this problem.
The first thing you'll notice about the PP445 is that they're bigger than standard dumbbells. They have to be taller in order to allow the use of multiple plates on the rack. Because of this, it may limit some of your sets. I tried out the PP445s with five routines of P90X: Tony Horton's 90-Day Extreme Home Fitness Workout DVD Program, which I think is a great litmus test because it involves dozens of different exercises that use a variety of moves to give you a good evaluation of how they will compare to standard dumbbells. Like the BST, there were only a few moves that I would have preferred standard dumbbells for - tricep extensions, and tricep kickbacks. The weight plates are so big that it can be tough to clear your chest on moves like this. However there is one advantage to having larger adjustable dumbbells, in that it encourages you to work your stabilizers, which is the main reason that free weights are so much better than machines to begin with. I found that on some of the moves that the PP445s size makes them unwieldy on, I have to concentrate more on my form to make sure the weight clears, and this can give me better results. Switching weights is extremely easy to do. You just turn a knob to select the desired weight amount, and it is very similar to the Bowflex. It will take you about 4 or 5 seconds to adjust the weight on both dumbbells. This is perfect for me since I like little downtown between sets, and want to spend that time focusing on my form and getting my mind right, rather than fiddling with a bunch of weights. The weights lift up easily and don't "catch" like I sometimes experience with the Bowflex when it isn't entirely locked into place. Although they can be a bit awkward until you get used to them, they feel just as well-balanced as traditional dumbbells. The stand feels sturdy and high-quality, and doesn't have a very big footprint. I do prefer the Bowflex stand since it has locking wheels on it so I can roll it out of the way if needed. Another reason I will continue to use my BST over these, is because I prefer the extra 7.5 pounds on the BST, which I need for heavier sets such as back exercises and squats. But mostly, I will use the BST because they are adjustabnle in 2.5lb increments, whereas the 445s can only be adjusted in 5lbs. For me, this is a huge disadvantage to weights that are only adjustable in 5 lb increments (and I would never advise anyone buy 10 lb increment weights). 2.5 lbs makes a big difference for me on a lot of sets, especially when using smaller muscle groups like biceps and triceps. If I had to make adjustments in 5 lb increments on an exercise such as pour flys (hold your arms straight out to your sides with weights, and then turn your palms down, like you're pouring out a beer), I would never get better because it's too much for me. Smaller increments allow me to advance while maintaining proper form. This is the main reason I purchased the BST over the PowerBlock (which is a decent dumbbell set, but a little too big for me).
In summary, I do think the Power-Pak 445s are a five-star product and very well-made. I do not think they are superior to the Bowflex SelectTechs, but if you want a much cheaper alternative than the Bowflex and don't need the extra 7.5 pounds it offers, this is a great alternative. In my list above, I would put them at number 2 above the PowerBlocks.