These are our 4" x 12" 4 Mil blue line economy Zip Locking plastic bags. The only difference between these 4 x 12 .004 mil zipper lock bags and our 2 Mil Clearzip bags is that these are in limited quantities. These 4 in. x 12 in. 4 mil zipper bags have a light blue line that runs through the top of the bag, just above the reclosable seal.