Ace Glass 7566-08 Inner Joint, Full Length, 7/25, 9 mm

Tubing is same diameter as reinforcing rings on the joint. Strain on the joint is reduced from expansion due to temperature increase. Properly clamped, the joint tends to remain cooler, with less tendency toward lubrication loss. Very heavy walls are not desirable for thermal shock resistance, but are desirable for resistance to mechanical pressure and shock. Therefore, providing reinforcement rings instead of a heavy wall results in a better, more balanced design. No holdup below the joint makes this an ideal joint for flask necks and receivers.