Abstract: Some embodiments are directed to a protective frame assembly. The frame assembly includes a first frame including an inner wall surface and an outer wall surface opposite to the inner wall surface. The inner wall surface includes a channel. The frame assembly also includes a second frame including a front wall surface and a rear wall surface. The rear wall surface of the second frame faces the inner wall surface of the first frame. The frame assembly further includes a spline received within the channel of the first frame. The frame assembly also includes a mesh sandwiched between the inner wall surface and the rear wall surface. The spline engages with the mesh within the channel to retain the mesh in a tensioned state.

Abstract: Some embodiments are directed to a protective frame assembly. The frame assembly includes a first frame including an inner wall surface and an outer wall surface opposite to the inner wall surface. The inner wall surface includes a channel. The frame assembly also includes a second frame including a front wall surface and a rear wall surface. The rear wall surface of the second frame faces the inner wall surface of the first frame. The frame assembly further includes a spline received within the channel of the first frame. The frame assembly also includes a mesh sandwiched between the inner wall surface and the rear wall surface. The spline engages with the mesh within the channel to retain the mesh in a tensioned state.

Abstract: A latch tongue of a lock has a pair of contact points which are respectively connected to the gate and the cathode of a silicon controlled rectifier. When the lock is closed, the latch tongue is in a latch tongue housing which connects the points together thereby providing a connection between the gate and cathode. Additionally, the closing of the lock with a key causes a series connection of the anode and cathode of the rectifier with a bell and a voltage source. When the latch tongue is removed from the housing, the gate to the cathode connection is broken thereby causing the application of the voltage of the source to the bell.