Membrane (A) heater or membrane for water body. 

Its membrane may be yellow. Junkers has changed all the membranes for these made of transparent silicone.

Characteristics: 

• With ear.
• Diameter: 51mm
• Inner diameter of ear: 6mm
• Outer diameter of ear: 11mm
• Engraved Letter Aluminum Shaft: A
• Aluminum Axle Height (where the letter A is engraved): 15 mm
• Aluminum Axle Height (where the letter A is engraved): 6.55 mm