As PC boards have become more advanced, the number of connector pins has increased, along with the force required to insert and eject the board. Generally speaking, the most pressure a person wants to put on the tip of their finger is 25 lbs. Calmark/Birtcher inserters and extractors take the struggle out of installing and removing boards, by providing a mechanical advantage. Two inserter/extractors are recommended per printed circuit board taller than 5” in height, one at the top and one at the bottom.