Polarizer filters give you several key creative features. They evenly increase color saturation of all colors (except black and white), creating deep, rich scenics. They add contrast for dramatic skies and ariel shots. They eliminate the whitish glare from highly reflected surfaces like glass and water. Polarizers are two part lenses that rotate, allowing you to select the degree of additional saturation, contrast and glare reduction desired. Tiffen polarizers are offered in standard and warm versions. Warm polarizers add Tiffen's exclusive 812 warming filter, giving portraits and scenics a warm and muted feel while retaining rich coloration. Polarizes come in two types: Circular -- for all types of cameras: required for beam splitting metering systems commonly found in auto-focus SLR's and in most curretn TTL Slr's. Linear -- for older metering systems. Tiffen polarizers are available in the follow variations: Standard Linear. Standard Circular. Warm Circular -- polarizer plus 812 warming filter. Wide Angle Circular -- a thin filter designed to avoid vignetting at the edges from larger wide angle lenses.