I'd like to give my 02 cents....my corn snake Skittles escape twice from his PLASTIC mesh lid, the lightweight ones, even when it had both cage clips AND books stacked on the sides of the lid. If your snake is crafty they can get out with a plastic lid! I found him both time he escaped as a baby, and he was so small I didn't even know he could reach the lid let alone crawl out. I swapped him onto a METAL lid and bam! He's in there good, not getting out. Cage clips are on there too.
So my recommendation: cage clips on a metal lid. Plastic lightweight lids will have your snakes escaping!!!