For a fairly reasonable price, you can get a decent quality pair of adjustable dumbbells.
Although not of the highest quality, the Rocketlok 100-Pound Adjustable Dumbbells are solid, well built, and it is a safe product to purchase, if you are going to be doing workouts in the home, and need to save space around the home.
Quality
The stainless steel plates are heavy, and the solid handle bar has a rubber grip, for optimal comfort.
The adjustment plates are solid, and well built, and with the simple lock into place feature, you do not have to worry about the plates coming loose when you are working out, or after you adjust and are lifting the dumbbell up above head during a workout routine.
Weight range & increments
When working out, the range is going to adjust from as low as 5 pounds, and up to 50 pounds; additionally, each of the set has different weight handle bars, so you can adjust easily, and add a few more pounds, if you are doing easier exercises.
The weight is going to adjust in increments of 2.5 pounds, which is another feature that other weights do not provide, making it easier to do more exercises, and a wider range of exercises.
Ease of change
A simple twist of the dial is going to lock the new weight into place.
Latching mechanisms are in place on the base, so that all you have to do is turn to the desired weight amount, twist down on the latch, and wait for the weight to click and lock into place; upon doing so, you can remove it from the base, and you can begin the workout you are going to do with the weight.
Handle
The handle is very comfortable, and makes for an ergonomic grip. Since you have the rubber base finish, you can easily adjust and hold in any position, and are going to find that it is more comfortable than other sets that you can purchase for use.
With different hold positions, you can also place your hands in a location that is most comfortable for you, so as to ensure you are going to be able to get a comfort grip, and will not drop the weight when you are working out with a heavier range during a routine that you are doing.
Customer Reviews 
Reviews for this product are mixed. On the plus side, the weights do lock into place , the plates are solid, it is easy to adjust, and it is a comfortable set to use.
But, there are quite a few negatives that you have to consider as well if you are going to buy this set; the main one being that the latches are not as safe as other products, as they are plastic coated.
Depending on the use, and how you are going to use the weights (above head, or seated exercises), this may be a good set for new users or beginners, but may not be a top choice for those doing high scale workout routines.