From the Highly Educated website...
"NEW Limited Edition 30MM Gavel V2 from Highly Educated featuring a 5mm opaque bottom.
- 30 mm diameter bucket
- 2.5 mm thick clear quartz walls.
- 5mm thick opaque quartz bottom.
- 14mm male precision ground joint.
- Compatible with 25mm GTR Caps & OG Riptide Caps.
The logo has been laser engraved into the joint keeping the branding subtle, but permanent. The chamfered edges on the top are made to accommodate a better fit for most bubble caps. The opaque surface is slightly textured which assists in the formation of nucleation sites at exceeding lower temperatures. The thermal transfer properties of the opaque make it more efficient at cooking than materials with superior thermal retention."