CO2 MANIA®'s external crystal glass bubble counters for aquariums are designed and built with the best materials in Asia and are all tested* in Italy. The machine-blown technical crystal glass structure and its finely artfully perforated circular shape make (01-CN-ExtBubbleCirc) very elegant, the precision of laser cutting pressed the count extremely precise, avoiding waste of gas. The circular bubble counter (01-CN-ExtBubbleCirc) is distributed by CO2 MANIA® and is recommended for Co2 type gases. _Technical features_ - Recommended minimum inlet pressure 3bar/43psi - Technical crystal glass bubble counter (length 8.5cm X width 2.7cm) - Direct coupling inlet connection for 4/6/8mm PVC pipes - Product tested* in Italy - We recommend applying it to the glass of your aquarium with suction cups. (not included)