Locking Liner - (a.k.a. linerlocks) This particular locking system was refined by knife maker Michael Walker. The actual locking mechanism is incorporated in the liner of the handle, hence the name. If there is a metal sheet inside the handle material, it is called a liner. With a locking liner, opening the blade will allow this metal to flex over and butt against the base of the blade inside the handle, locking it open. Moving this liner aside will release this lock allowing the blade to close. Disengagement of the lock is performed with the thumb, allowing for one handed, hassle free action. Locking liners are commonly found on tactical folding knives, both production and custom.