High-purity, ash-free filters (White Ribbon brand, FS grade) manufactured from laboratory filter paper (GOST 12026-76) and acid-treated. These 70mm diameter discs offer a filtration time of under 45 seconds and effectively retain precipitates similar to cold-precipitated lead sulfate.
<img src="ash-free-filter-70mm.jpg" alt="70mm Ash-Free Filter">
US: temporary delays — postal services aligning new import rules, 
EU: 1–2 weeks, 🌍 Worldwide: 1–4 weeks ✈️