This article explains the differences between the vast variety of external storage enclosures and gives you some tips and recommendations on how to choose the right one for your particular device.
	Depending on the device you would like to install, the enclosures are sorted by sizes of 1.8", 2.5", 3.5", 5.25", Slim Type CDRW/DVD and other custom made cases. • 1.8" hard drives are not very common on the market but are used in products such as the iPod as an example. The drives are usually not available separately, so we suggest you to buy a finished product. • 2.5" hard drives are the drives used in Notebooks. The most common ones are 9.5mm thick and fit in all 2.5" enclosures. The not so common 12.5mm or rather old 17mm thick hard drives will only fit in a few enclosures. For the 12.5mm drive we recommend the Clearlight or the Daisycutter, for the 17mm drive we do not provide any enclosures. • 3.5" hard drives are the drives used for desktop computers and come in standard sizes. Any enclosure made for those will fit but remember to check if they support the latest ATA-6 drives. IceCube Generation II or MantaRay. • 5.25" devices are optical devices such as CDRW or DVD burners designed for desktop computers. They vary in length but the enclosures are made to house any length. HotButtered CDRW or HotButtered DVDRW. • Slim Type CDRW/DVD are optical devices such as CDRW or DVD burners designed for notebooks. The dimension vary from manufacturer to manufacturer, so we suggest you to buy a finished product, rather then finding your own enclosure. Cold Chisel CDRW/DVDROM.
	Smaller drives (1.8" & 2.5") are usually powered by bus power, meaning it does not require an external power adapter. As bus power is not always guaranteed, we recommend you to look for an enclosure which provides a DC jack for an optional power adapter, just in case. Bigger drives (3.5") and optical drives require an additional power supply. The choice you have are external power adapters and internal power supply. External Power Supply: Advantages are a fanless enclosure and smaller footprint/size of the casing, disadvantages are additional cables and a part which can be easily lost or forgotten. Internal Power Supply: Advantages are a compact and convenient casing, disadvantages are a bigger enclosure and fan noise.
	Enclosures for 3.5" hard drives and optical devices will either come including an onboard fan or with fanless design. If you are going to use this device 24 hours a day, we recommend you choose an onboard fan. If you only use it a couple of hours every day or for temporary backup, a fanless design will be ideal and practically noiseless. Keep in mind to leave enough room and air around the unit to avoid overheating.
	The most common material used for the body and casing nowdays is aluminium. This material provides excellent heat dissipation, offers a nice touch and simple but elegant design. Polycarbonate plastic in comparison comes in many colours as well as translucent. Most aluminium enclosures do not offer a lot of shock protection, so for mobile drives (2.5") you might want to consider protecting it by using protective soft bags as an example. An enclosure with additional shock protection is the Clearlight, coming in translucent polycarbonate plastic.
	The interface you choose depends on your requirements. Very fast connections like Firewire 800 or Serial ATA are usually recommended for hard drives with high rotational speed, USB 2.0 and IEEE 1394a (FireWire 400) are most commonly used for standard products with a very good compatibility and optical devices. To be flexible, you might want to consider a slightly more expensive combo solution with two or even three types of interfaces on the same case.
	The most important part of the bridge board used inside the external enclosure is the chipset. This key component defines most functions, performance and features of the enclosure. For detailed descriptions check out the website of the silicon manufacturer.
	Compare the features such as LED indication, stackability, feet for upright usage, special buttons and other functions. Most bridge boards designed by Macpower use Over Voltage and Low Power Protection as well as Inverse-Polarity Protection.
	Last but not least, the pricing. This will depend on the chipset used, the interface, the material of the case and the power supply. Even though the combo units are most likely slightly more expensive then a pure USB or Firewire solution, those extra few dollars are worth it, if you want to stay flexible and up to date.