Lids are metal and screw on smoothly. Rollers work great. No leaks, I have purchased several packs of these to make my castor oil ginger roll ons for family and coworkers. No one has had any issues with them, they work perfectly. I also ordered some with plastic Lids, those did not seal well, they did not screw on correctly and the rollers would not dispense the oils. I recommend these!