The Fabric Interconnect F1-15's I/O Modules have a locking mechanism to secure the modules into the chassis. The locking mechanism (a quarter-turn Pawl) is embedded in the I/O Module handle, which has a slotted head. By using a screwdriver, you can turn the I/O module handle in a 90-degree arc to lock or unlock the I/O module. For more information, see Using the I/O Module Lock.