An optically active glass and an optical fiber comprising such glass, having reduced photodarkening properties are provided. Various sensors separately provide disparate analog signals representing different measurable attributes regarding sensed object. The device further includes at least two outrigger wheel assemblies coupled to the platform and biased toward the riding surface to improve stability of the riding device during sharp turns. A retention device to limit radial movement of the filtration media when subjected to the periodical cleaning fluid and to maintain the pleats in the filtration media circumferentially spaced apart when exposed up to 130 degrees Celsius. The frame system includes a plurality of frame members, a hinge that couples the frame members together, and a lock that blocks relative movement of the frame members. The first housing forms a combustion chamber for the gas generant.