It's important. Is the kit secure? Why couldn't it be safe? -- The tank: is it plastic? Two items you're searching for: If so, note that certain Nicotine Salts E-liquid, which is not ideal, can degrade the plastic. Glass is, we assume, the road forward. -The battery: is it health characteristics? Short circuit auto shut-off? The more reliable, the more protection apps. -- Metal: What's the source? Do RoHS approve it? RoHS is licensed to goods following testing to prove that no lead material is usable. We saw Kanger tank clones starting to rust after some time as the content used is not stainless steel but some low-cost metal alloy.