These are our 3" x 10" 4 Mil blue line economy Zip Locking plastic bags. The only difference between these 3 x 10 .004 mil zipper lock bags and our 2 Mil Clearzip bags is that these are in limited quantities. These 3 in. x 10 in. 4 mil zipper bags have a light blue line that runs through the top of the bag, just above the reclosable seal.