20-sided DICE

Usually denoted by D20 and also called icosohedron or icosaeder (except the so-called spindle D20's).

Relative old ones with the 6, 9, 16 and 19 underlined ...

... and more recent ones with a dot behind the 6, 9, 16 and 19 ...

... and transparent ones and micro dice.

On the left a D20 with 2 times the numbers 0 to 9, and
on the right a D20 with the numbers placed inside 3 '<-signs'.

D20's known as Crystal Dice.

Some D20's with two times the numers 0 to 9, a D20 with letters, and a large plastic D20.