Inside the plastic casing is a small printed circuit board, which has some power circuitry and a small number of surface-mounted integrated circuits (ICs).[citation needed] Typically, one of these ICs provides an interface between the USB connector and the onboard memory, while the other is the flash memory. Drives typically use the USB mass storage device class to communicate with the host.[28]
The memory in flash drives is commonly engineered with multi-level cell (MLC) based memory that is good for around 3,000-5,000 program-erase cycles,[40] but some flash drives have single-level cell (SLC) based memory that is good for around 100,000 writes. There is virtually no limit to the number of reads from such flash memory, so a well-worn USB drive may be write-protected to help ensure the life of individual cells.
Many types of USB drive, sometimes referred to as a thumb drive, also have handy features like a key chain ring or a small LED flashlight. Some can even transmit your data wirelessly for the ultimate in digital convenience. And as with any fun accessory, there are plenty of novelty versions of flash drives designed to show your personality, display your sense of humor, or broadcast your team loyalty.
