Hitachi has introduced a line-up of 2.5-inch hard disk drives, the Travelstar 4K40 series, which have a high shock-proof specification that makes them suitable for notebook PCs.

The rotational speed is 4,200rpm and the media data transfer rate is 370Mbps.

According to the maker, the proof-proof spec of 30G (operating shock) and 100G (non-operating shock) are the industry's highest among 4,200 rpm, 2.5-inch HDD products.

The specification for load/unload cycles -- the number of times the read/write head can move on and off the media without failure -- is doubled to 600,000 times compared to HGST's current products.

The Travelstar 4K40, is available in 20GB, 30GB and 40GB capacities.