A new series of hollow-shaft right angle helical gear drives from Sterling Instrument (ISO 9001:2000+AS9100B Registered Manufacturer) feature built-in keyways plus left or right hand rotation. They are identified as the S991HY-... Series and feature heavy-duty sealed ball bearings, 1:1, 2:1 or 3:2 ratios plus rated speeds up to 1200 rpm. They are suited for most industry applications such as for use in printing, packaging and textile machinery. They are made with an aluminum alloy, hard-anodized case, 1144 steel, hollow bore shafts, and 4140 heat-treated steel gears. Their hollow-bore sizes range from 5/8" to 3/4" and their maximum operating temperature is 200 degrees F.