Actually a form of synthetic rubber, neoprene is widely used in a number of cases and carriers for tablets. The neoprene tablet case offers impressive resistance to outside elements (especially moisture and extremes in temperature) for such a soft, pliable material.
Thanks to its natural flexibility, neoprene also provides one distinct plus missing in most other materials from which tablet cases are crafted: A tablet envelope or sheath can stretch to fit the device for the sheerest possible fit. Some electronics accessory manufacturers produce full-on neoprene tablet bags and tablet sleeves. Most case styles in neoprene are further insulated with a thin bit of foam padding within the material for some extra protection. The neoprene may also be treated for more softness as opposed to the standard rubbery feel.
Another great advantage to neoprene tablet cases and bags is in their maintenance. Unlike virtually every other sort of tablet carrier, a neoprene carrier may simply be machine washed and air dried to look like new again.