Hexagonal shisha charcoal: H20 or H21?
The retail standard is H20 (20 x 50 mm): it snaps into two even 25 mm pieces for small bowls and fits most printed hex boxes on the market. H21 (21 x 45 mm) is shorter and a little heavier per stick, which suits lounges loading whole sticks around a phunnel bowl. Both are rated for 120 minutes at 80% fixed carbon with white ash at 1.9% maximum.

