The POSITAL IXARC OCD-S101G-0012-T080-2RW Optical SSI with Preset encoder provides 12 bit resolution along with excellent dynamic response and is suitable for use in areas with high magnetic fields. A Aluminum flange, Aluminum housing and void temperature range provide IP65 environmental protection. Since the rotation of the code discs is an entirely mechanical process, there is no risk of these devices losing track of their absolute position due to a temporary loss of instrument power. No backup batteries are required!