As successor of the 600 series, the T series became IBM mobile productivity line. Usually leading the ThinkPad range in technology, innovation and price, the T series was intended for the travelling businessman - comparatively more stylish, functional, and rugged machines; and easy to disassemble for repair or upgrades. T series ThinkPads are clad in black non-slip rubber with embedded glitter. The case lid has tabs along the edge that interlocks with depressions in the lower case when closed, to reduce case flexing.