Frame-less shower doors do not have a metal frame around the edges. The hinges and handle for the shower door are the only visible pieces of hardware. Without the frame, frame-less shower doors need to be thinner. Compared to framed shower doors, frame-less showers can have glass up to 1/4 inch thinner than that in framed doors.
The frame on shower doors supports the glass, which is usually 1/2-inch thick. Hinges for the door are also built into the frame rather than the glass itself. Framed shower doors rely on the shower frame or the wall to hold the hinges on the shower door's frame.
When considering a frameless shower door as a replacement for the frames for your shower, you cannot use your old door with the frame removed as the door for your frameless shower. The door frame was hinged to the frame around the shower or to the wall. Since the hinges were built into the frame and not the glass, when you remove the frame, you will have a solid piece of tempered glass, which cannot be cut to accommodate the screws for the hinges. You need to buy a new frame-less shower door.
Glass used in a shower must be tempered to prevent shattering, but this tempering process must be done after the glass is cut. Though tempering strengthens the glass, a small cut on the surface causes the entire piece to shatter into nuggets. When installing frame-less shower doors, you need to buy a tempered glass door cut and drilled before tempering.