How it latches

Press on, press off

The switch has two pins and one contact between them. On its own a contact like that would close while you press and open when you let go, which is what a push button does. This one has a latch: every full press turns it a step, and alternate steps hold the contact closed after you let go.

So one press turns it on and it stays on. The next press turns it off and it stays off. The back of the board says exactly that: PRESS TO TURN ON, PRESS AGAIN TO TURN OFF.

The figure draws the latch as a wheel. That is a picture of what it does, not of how this switch is built inside: the switch's drawing shows only the outside. It also does not say at which point of the stroke the contact changes. For a sketch it does not matter. What your board sees is the level before the press and the level after it.

A firm press

The switch is a 12 × 12 mm body, 4.5 mm tall, with a 5.4 mm round button, and on the board its top stands 9 mm above the board. Its drawing gives the force to operate it as 700 ± 100 gf. That is roughly the weight of 0.7 kg resting on a fingertip: a deliberate press, not a tap.

The same drawing rates the contact for 30 V and 1 A DC and at least 50,000 cycles. On this board the contact carries a few milliamps at 3.3 or 5 V, a very small fraction of that rating.

Read the LED, not the button

The drawing gives the button one height, so don't expect to see whether it is on from the button itself. The red LED under the switch is wired to SIGNAL, so it lights exactly when the switch is on. It is the switch's own indicator and it works with no sketch at all, as long as VCC and GND are connected.

Against the push button

The TK04 push button is the block with a switch that springs back. It reports a press only while a finger is on it, so a sketch has to catch the press and remember it. This one does the remembering itself. That makes it the right block for a choice that should stay made, such as a mode, and the wrong one for anything you press often.