Collapsible extended surface filter and air cleaner system using collapsible extended surface filter

A filter for an air cleaner having an enclosing structure including a first wall, a second wall and two side surfaces, the filter comprising:

• a pleated media filter having a first end, a second end, and a filter media having a pleat edge and an end portion, a portion of the pleat edge is included in the end portion;
• a first end structure provided at the first end of the pleated media filter and a second end structure provided at the second end of the pleated media filter such that the pleated media filter extends between the first and second end structures;
• and a flexible support member having a first end and a second end, the first end coupled to the first end structure and the second end coupled to the second end structure such that the flexible support member extends between the first and second end structures,
• wherein the collapsible filter is designed such that:
• when the collapsible filter is placed into the enclosing structure, it is maintained in an extended state by a system comprising multiple support arms extending from the first end member to the second end member and across the flexible support member.