Must have. It's more expensive than most, but worth it in my opinion. I like a pen that equalizes internal and external pressure before you use it. My only downside is that you can see from the photo that it has a bright white dial, but the actual product has a darker background which reduces the contrast. Eliminating the intermediate numerals (25, 35, 45, etc.) from the dial would likely improve legibility even further. After all, the advantages of "liquid filling” were not explained anywhere.