Tiffen "4x4 POLARIZER" Polarizing filters are used to reduce reflections and deepen the color of the sky. We will ship with a tracking number within 24 hours of purchase. The size is 4" x 4" with a thickness of 4mm, a common size for cinema filters. (4 inches on one side = 101.6mm) Many matte boxes support both 4" x 5.65" and 4" x 4" filters (e.g., Smallrig, Bright Tangerine, Chrosziel). We've priced it very affordably, so don't miss this opportunity! Please consider it.