This is a soundproof lock for narrow frames.
GT10
■  Most appropriate for narrow frame aluminum doors This lock's compactly designed case suits it for use in doors less than 2,200mm high.
■  Excellent soundproofing
The  upper  and  lower  rods  and  the  deadbolt  projected  by the lever handle bring the door and jamb into close contact for optimum soundproofing.
■  Trigger bolt prevents damage
The  GT1151  trigger  bolt  insures  that  the  lever  handle  can be operated only when the door is closed, to guard against damaging or scarring the jamb, door or ceiling.
■  Easy installation
Upper  and  lower  rods  are  on  the  same  axis,  making installation easy.