Sometimes the simple solution is the best!

If cost is an issue and/or you have many opening sizes or color needs for mats - you may want to check out the option of using only a backer board and a re-sealable poly sleeve.

These packages are ideal for that purpose!

Choose the backing board you wish to use and the size.  Bags will automatically be added to your order in the appropriate size.  Four standard sizes to choose from at prices lower than the individual items.

Check these out here!