A dumbbell is a piece of free weight equipment - it is a short metal bar with weights on each end. Generally, dumbbells comes as a fixed weight dumbbells or as fully adjustable dumbbells.
Fixed size dumbbells are usually cast as a single piece of some material, usually iron. Such dumbbells usually have rubber or plastic coating to protect them from rusting, but also to lessen the potential damage when dumbbells are dropped from height.
Iron, fixed size dumbbells come in many shapes and weights, often ranging from 10kg to 50 or more kilograms. Dumbbells lighter than 10kg are often made out of plastic filled with sand or similar material. When small dimensions are required, even lighter dumbbells are made out of cast iron with rubber coating.
If you are purchasing dumbbells, be sure that they have good coating, since it protects dumbbells from damage, but also it helps avoiding damage done by dumbbells.
Most of the commercial gyms have fixed size dumbbells - they do require more space and they weigh more than adjustable dumbbells, but they can be used by several trainees at the same time, they last longer and switching from weight to weight is much faster, even when compared with adjustable dumbbells with dial-in mechanisms.
Adjustable dumbbells come in several forms. Using short bars and adding weight plates creates simple adjustable dumbbells - such adjustable dumbbells are cheap and require time for changing the desired weight. Also, collars must be used for securing the weight plates on the bars and this prolongs changing weight.
However, to acquire some specific weight or large weight, such adjustable dumbbells are the only solution.
Adjustable dumbbells with dial-in mechanisms (also known as 'selectable dumbbells' or 'dumbbells with selector') allow wider weight range with less available weights. Modern dial-in mechanisms allow weight change in just few seconds and are robust enough to last for a long time - just be sure not to drop the dumbbells on concrete or similar hard surfaces. These dumbbells eliminate the need for multiple dumbbells having around which is great for home gyms.
Price for such sets appear high, but in the long run, one saves both money and space.
Fixed size and adjustable dumbbells reviews and recommendations, ordered according to the date added or modified:
Universal Power-Pak 445 Adjustable Dumbbells with Stand (Combo) is great adjustable dumbbells set for any home gym. They require little space and changing between weights is quick and easy.
Cap Barbell 40-Pound Dumbbell Set is set of two adjustable dumbbells in plastic carrying case. Price is very acceptable, especially when compared with adjustable dumbbells that have various plates changing systems - on the other hand, changing weights on such dumbbells is faster.
Bowflex SelectTech Dumbbell Stand is robust and sturdy dumbbell stand - ideal for adjustable dumbbells, like Bowflex SelectTech 552 or 1090.
Bowflex SelectTech 552 Adjustable Dumbbells adjust from 5 to 52.5 pounds (2.26 - 23.8 kg) rapidly and thus eliminate the need for multiple dumbbells having around - great for home gyms. Price for such set appears high - but, in fact, one saves both money and space.
Bowflex SelectTech 1090 Adjustable Dumbbells adjust from 10 to 90 pounds (4.53 - 40.8 kg) quickly and easily, thus eliminating the need for multiple dumbbells having around. This is great solution for home gyms, not so for commercial gyms. Price for one or two dumbbells appears high but, in fact, such dumbbells in the long run save both money and space.