90° 10mm E.Ross 4.0 x Groe Tourbillon.  It features 4 holes for extra airflow and an extra thick 3/16 inch polished quartz disk on the bottom. 
25mm Quartz Bucket
-Features 4 holes drilled at an angle, so when you cover the top, air spins inside the bucket. Great for spinning beads.
-2.5mm wall thickness
-25mm OD, 20mm ID
-Slight bevel to ensure a marble seals it without thinning the rim