Models HS35 (3.5" dia.) and HS25 (2.5") incremental hollow-shaft encoders are available with the Class 1, Division 1, Group C and D ratings (Eex ia IIB T4 CENELEC) when connected to the appropriate intrinsic safety electrical barriers. This extends the hazardous environment capabilities offered in the existing HS35 package and introduces the new, smaller hollow-shaft style of the HS25 package as solutions for these demanding applications. Both encoder styles offer an RS-422-compatible output, along with an intrinsic safety rating. The hollow shaft encoders can be mounted directly to shafts with diameters ranging from 1/4" up to 1", resulting in compact installations. The intrinsic safety rating is well-suited to providing precision measurement in hazardous environments, such as explosives handling and industrial process controls involving flammable substances.