Tecmark TBS123A Air Switch / Pneumatic Switch.
This is a SPDT single pole double throw switch (there are 3 quick connect terminals. The middle terminal is a common and every time you activate the air switch the common toggles between the other 2 terminals).
Power: 250vac 16amp resistive (i.e.. Heater) and 4amp inductive (i.e.. Pump).
Hole size required : 15mm.
Pipe Size required: 3mm.