The Meinl Snare Cajon and Toca Snare Cajon come with a fully adjustable snare on the inside that is in contact with the faceplate.
To control the cajon snare effect, tighten or loosen the knob and adjust the snare levels or turn it all the way off.
When the snare is in light contact, the snare effect is the strongest.
And if you want the snare off, back the knob off and retighten it in position and the snare effect will be gone.
If you take the faceplate off of the cajon, you can see exactly how the snare effect works.
Look closely at how the knob on the outside connects to the snare wires on the inside.
As you roll the knob forward, the snares come in contact with the inside of the faceplate.
As you roll it back, the contact is reduced.
So, with close precision, you can carefully set how much snare effect you want on your cajon.
Related Reading: How to Adjust the Top Corners of a Cajon for Slap / Crackle Effect