Grab
If the creature hits with the indicated attack (usually a claw or bite attack), it deals the normal damage. If the attack roll result equals or exceeds the target’s KAC + 4, the creature also automatically grapples the foe. (If it equals or exceeds the target’s KAC + 13, the creature instead pins the target.) The creature doesn’t need to have a spare limb free to perform this grapple as long as it can make the listed attack, and it can potentially grapple more than one target if it has more than one attack with the grab ability. The creature can maintain the grab either with another successful grab attack or by performing the grapple combat maneuver normally.
Format: Melee claw +8 (1d6+4 plus grab).
Source
Alien Archive pg. 155