Abstract: Implementations of a filter holder may include: a mounting bracket having two or more T-shaped brackets slidably coupled with each other each with a first part and a second part, the first part being substantially perpendicular to the second part. A disc may be included. Two or more clamps, each coupled to the second part of each of the two or more T-shaped brackets may be included which couple to a filter. The disc may be slidably coupled to the first part of each of the two or more T-shaped brackets. The slidable coupling of the two or more T-shaped brackets may allow the T-shaped brackets to accommodate a dimension of two or more differently sized filters.

Abstract: A method and system for comparing cost of shipping options are provided. The method includes determining, with a computer system, based on shipping data input into the computer system, a first shipping cost for shipping the package using a first mail carrier; determining, with the computer system, based on the shipping data, a second shipping cost for shipping the package using a second mail carrier; calculating, with the computer system, a cost difference between the first shipping cost and the second shipping cost; outputting by the computer system the cost difference; and periodically sending the cost difference for shipping the package or a plurality of packages to an individual or organization monitoring shipping costs.