They are ok and they do the work i made a video how they work they claim to be 4mm but i do not think so they do not feel heavy duty as they claim but they work fine i made a couple of test and i did not have any problem with them

I usually use the vacuum sealer for a sous vide and i use these bags to cook some chicken breast in my suvi they worked fine and did not open they maintained the seal during the cooking in the suvi and even after i put some of the breast in the freezer and they worked fine even when they performed fine i did not like the feeling of the material i was expecting something more sturdy and my expectations were not met i was expecting them to be more robust