Apparatus for collecting light from an LED and transmitting it in a near-uniform column incudes a conical reflector about the base of the LED for collecting light emitted to the sides of the LED, and a lens specially designed to focus the collected light into a near-collimated beam. Circuit emulation entities are selected via the interaction with the tool in a combination of configuration and selection contexts. At least one infeed cone is provided upstream of a seal seat to centre the shut-off needle, the lower end of which forms a shut-off part.