This item comes with 10 single mats, 10 backing, and 10 bags. The opening size is 11.5x17.5 for 12x18 print + backing board + clear bag The mats are
BLACKCORE MAT, 10 of 18x24 Black Pre-cut Acid-free for 12x18 +back+bag
Acid-Free Custom Cut White Photo Matboards 18x24 mat pre-cut for 16x20-inch pictures, photos, and artworks Mat Opening Size: 15.5 x 19.5 White Core,
Mat Board Center, Pack of 10, 18x24 for 16x20 White Photo Picture Mats - Acid Free, 4-ply Thickness, White Core - for Pictures, Photos, Framing
Our Acid-Free matboards are 4-ply and feature a White Core. With an overall size of 8 inch x 10 inch, these mats fit perfectly into 8 inch x 10 inch frames. Each mat is bevel cut to enhance your 6 inch x 8 inch photos. The actual mat opening size is 5.5 inch x 7.5 inch inches so that it may safely and securely display your 6 inch x 8 inch photo, artwork, needlepoint, sign, etc.
12x18 Mat for 18x24 Frame - Precut Mat Board Acid-Free Aqua Blue 12x18 Photo Matte for A 18x24 Picture Frame, Premium Matboard for Family Photos, Show
12x18 Opening for 18x24 Frame 6-ply Mat
18 x 24 Deluxe Black Aluminum Contemporary Picture Frame, 12 x 18 – The Display Guys
Mat Board Center White Color Mats - Bevel Cut Acid Free 4-ply Thickness White Core - for Pictures Photos Framing Pack of 2 18x24 for 12x18
Pack of 10 Textured White Precut Acid-Free Matboard Set with Clear Bag – Poster Palooza
18x24 Navy Blue & Silver Double Picture Mat, Bevel Cut for 12x18 Picture or Photo : מוצרי חשמל
PosterPalooza 12x18 Mat for 18x24 Frame - Precut Mat Board Acid-Free White 12x18 Photo Matte Made to Fit a 18x24 Picture Frame - ShopStyle
THIS IS FOR ONE SINGLE MAT without backing and bags , Featuring a picture opening for a 16x20 inch photo, to fit in a 20x24 inch picture frame. Photo
20x24 Mat for 16x20 Photo - Precut White on White Double Mat Picture Matboard for Frames Measuring 20 x 24 Inches - Bevel Cut Matte to Display Art
Pack of 2 22x28 Double Acid Free White Core Picture Mats Cut