K20, the clamping element that serves as a gluing aid for work pieces that are difficult to clamp, e.g. bulkheads, HVAC chases, etc. K20 is applied alternately with biscuits and holds the work piece in position until the glue in the biscuit notches has dried.

Plastic element with lateral clamping ridges for anchoring in the groove
Used in combination with biscuits
Can be installed with any biscuit joiner