Officially in the Mapex catalogues this is called called the "Pneumatic-adjustable throw-off". However, it's far more commonly referred to as the "Orion throw-off" as the snares supplied with all Orion series kits (initially Black Panther branded, later Orion branded) came with it fitted after about 1997.

Most standard depth Black Panthers (5" and above) from 1997 up until the range refresh in 2010 come with this throw-off, apart from a few models in the very early days that used the twin-cam throw-off and some special editions that used the Saturn standard one. It continued to be used extensively in Japan for custom builds after this date though, and for a short while in the west for some special editions. 

The associated butt-end also has an adjustment dial to perfectly centre the snare on the head.