The Polarizer/Analyzer for Optics Expansion Kit (PAK-OEK) includes two adjustable polarizer/analyzer and a third unit designed to incorporate either the Rotary Motion Sensor (RMV-BTD) or the Go Direct® Rotary Motion Sensor (GDX-RMS). The polarizing film on each of these polarizers/analyzers is made of cellulose triacetate substrate, which has a 38% single pass light transmission for unpolarized incident light.