The Zip drive is a medium-capacity removable disk storage system, introduced by Iomega in late 1994. A set of read/write heads mounted on a linear actuator flies over a rapidly spinning floppy disk mounted in a sturdy cartridge. The disk has all of the 9 cm (3.5") floppy's convenience, but holds much more data, with performance that is much quicker than a standard floppy drive (though not directly competitive with hard drives). The original Zip drive had a data transfer rate of about 1 megabyte/second and a seek time of 28 milliseconds on average, compared to a standard 1.4 MiB floppy's 500 Kbit/s transfer rate and several-hundred millisecond average seek time. The initial Zip system was introduced with a capacity of 100 megabytes. Unlike other diskette formats, the Zip's write protection is implemented on the software level instead of mechanically enforced in the hardware. The metadata on the disk indicates the write protection status, which the software driver then enforces to the operating system. This means that the disk must be loaded in a drive and accessed on a computer to turn write protection on or off. It also means that, in theory, a rogue driver could be created which ignores the write protection flag.