New posts in Components

Please help me identify this odd-looking component

Is there a gap in an LED between the plates (post & anvil) or a wire (or are there different kinds of each)?

What component is this (not a capacitor but looks like it)?

Does this sort of "multi lane" switch exist?

What kind of electronic device is this?

In what cases may component "Tempering" be required prior to assembly?

Date code in components marking

What's a potentiometer with four terminals in this schematic?

Why would I use 2N3904 instead of 2N4401?

What's cheaper & faster for my lab, keep a stock of electronics components or order?