My head loves the Lazer helmets. I have a Z1 that is going to be replaced soon (though it has been replaced but with a temporary helmet till I can get a new one)

I did have a Giro Synthe back in the day but I got a size M and should have gotten the L but they day I tried it on and the subsequent days the M fit fine but I realized I was going to want stuff for winter and that was just a little bit too small.

You needed to replace that old helmet 13 years ago. Please don't buy used helmets you have no idea what happened in that helmet and may never know and the seller probably won't give you the truth or the full truth. They could have crashed or could be a heavy sweater or both or it was stored poorly so many different factors and reasons to never buy a used helmet. It is safety equipment and beyond some really expensive testing that isn't worth it you will never know what happened and if you need to use your helmet and it was previously compromised it could be a bad day. Luckily it sounds like you haven't needed to use it at all and was just a fun head decoration which is what we all hope for in our helmets. Crashing sucks.