What does "internally-beaded" mean?
When a frame is described as "internally-beaded" it means that the beading itself is located on the inside of the frame (ie, facing into the room).
The "beading " is the part of the frame holding the glass in place, usually a plastic strip at the edge of the glass which snaps securely into the recess.
Beading can, however, be removed with careful prising, which is why beading on the inside of the frame (ie, "internally-beaded") is obviously much better for security. Safestyle's Diamond Windows come internally-beaded as standard.