Ceramic Mini Lessing Ring and Ceramic Raschig Ring are not interchangeable even at the same nominal size. DAIER's verified 50, 80 and 100 mm data show that Mini Lessing Ring provides substantially greater geometric surface area, while Raschig Ring has lower dry packing factor and, at larger matched sizes, lower packed-bed weight. Particularly at 80 and 100 mm, nearly identical or identical packing populations produce very different surface areas, demonstrating that internal element geometry—not pieces per cubic meter alone—controls the packed-bed position.

Plastic Pall Ring and Plastic Ralu Ring occupy overlapping but different random-packing positions. DAIER's catalog-confirmed same-size data show that Pall Ring has stronger surface-area and voidage characteristics at 25 mm, the two have almost identical surface area at 38 mm while Ralu Ring has higher voidage, and 50 mm Ralu Ring provides both higher surface area and voidage while Pall Ring provides lower dry bulk density. Because the current verified Ralu Ring data do not include dry packing factor, final hydraulic selection should rely on confirmed project-specific data rather than assumed pressure-drop advantages.

Metal Conjugated Ring is available in DAIER's catalog-confirmed 16–80 mm series. Surface area decreases from approximately 313 to 81 m²/m³ and packing population falls from about 211,250 to 3,980 pieces/m³, but void fraction is non-monotonic and dry packing factor changes only slightly between the 50 and 80 mm models. Final selection should therefore use exact supplier-specific physical data, tower diameter, fouling, mass-transfer duty and hydraulic requirements rather than assuming that the largest size automatically provides the most open or lowest-resistance bed.

Metal VSP Ring is available in DAIER's catalog-confirmed 25, 38, 50 and 76 mm series. Specific surface area decreases from approximately 196 to 67 m²/m³ and dry packing factor decreases from 212.2 to 72.9 m⁻¹ as size increases, but void fraction peaks at 50 mm and bulk density rises again at 76 mm. Final size selection should therefore balance mass-transfer area, hydraulic requirements, fouling, tower diameter, bed weight and actual element thickness rather than assuming that the largest packing is automatically the most open or lightest.

Plastic Pall Ring and Teller Rosette are distinct plastic random packings. DAIER's catalog-confirmed comparable-size data show that Teller Rosette provides substantially greater geometric surface area, while Plastic Pall Ring provides higher void fraction, fewer elements per cubic meter and lower dry packing factor. Final selection should balance contacting requirements against hydraulic capacity, fouling, tower diameter, polymer compatibility and retrofit constraints rather than treating the two geometries as interchangeable.