A theft deterrent device includes a locking portion and a housing portion. The locking portion includes a locking mechanism. The housing portion includes a housing portion wall. The housing portion wall comprises a first material and is configured to house a second material within the housing portion wall. The second material is made of a different material than the first material. The second material is selected such that a cutting tool will be hindered when trying to cut through the housing portion.

A bicycle locking device including a shackle with first and second arms, a lockable crossbar releasably engaging the first and second arms to form a closed loop with the shackle. The shackle and crossbar including an inner core, with an outer topside and an outer underside. At least one plate of high performance material is secured to the topside and underside of the shackle and crossbar to sandwich the inner core therebetween. The high performance material is harder and more brittle than the inner core.

A bicycle locking device including a shackle with first and second arms, a lockable crossbar releasably engaging the first and second arms to form a closed loop with the shackle. The shackle and crossbar including an inner core, with an outer topside and an outer underside. At least one plate of high performance material is secured to the topside and underside of the shackle and crossbar to sandwich the inner core therebetween. The high performance material is harder and more brittle than the inner core.

A security device has a metallic elongate body with at least one end attachable to a lock unit. The body has at least one track of material of the kind referred to above extending longitudinally on the surface thereof and metallurgically bonded therewith. The material of the track has particles of a hard cut-resistant material dispersed in a self-fluxing matrix of lower melting point than that of the body and comprising one of nickel, iron and cobalt in composition with chromium, silicon and boron. The tracks are normally applied to the elongate body by welding, preferably laser welding or laser cladding, but plasma arc welding or brazing might also be used. The lower melting point prevents melting of the elongate body while enabling the metallurgical bond. Tungsten carbide is the preferred hard cut-resistant material, but other materials might be used, such as silicon carbide, cubic boron nitride, or industrial or synthetic diamond.

A tamper-proof padlock box which locks a door to a door frame that ensures that only users with a specialized key can access and open an internal lock. The tamper-proof padlock box includes a guard lock box, a padlock, and a key-receiving track mechanism. The padlock includes a U-shaped shank and a locking body. The guard lock box includes a tubular body, a bottom, a removable top, and a staple-receiving hole. The removable top is slidably mounted to the tubular body and supports the padlock. The U-shaped shank is rotatably mounted to the removable top about a leg of the U-shaped shank. The leg is oriented normal to the removable top. The staple-receiving hole allows a padlock staple access to the padlock and normally traverses through a rear sidewall. The key-receiving track mechanism is mechanically integrated into the bottom.

A tamper-proof padlock box which locks a door to a door frame that ensures that only users with a specialized key can access and open an internal lock. The tamper-proof padlock box includes a guard lock box, a padlock, and a key-receiving track mechanism. The padlock includes a U-shaped shank and a locking body. The guard lock box includes a tubular body, a bottom, a removable top, and a staple-receiving hole. The removable top is slidably mounted to the tubular body and supports the padlock. The U-shaped shank is rotatably mounted to the removable top about a leg of the U-shaped shank. The leg is oriented normal to the removable top. The staple-receiving hole allows a padlock staple access to the padlock and normally traverses through a rear sidewall. The key-receiving track mechanism is mechanically integrated into the bottom.

A tamper-proof padlock box which locks a door to a door frame that ensures that only users with a specialized key can access and open an internal lock. The tamper-proof padlock box includes a guard lock box, a padlock, and a key-receiving track mechanism. The padlock includes a U-shaped shank and a locking body. The guard lock box includes a tubular body, a bottom, a removable top, and a staple-receiving hole. The removable top is slidably mounted to the tubular body and supports the padlock. The U-shaped shank is rotatably mounted to the removable top about a leg of the U-shaped shank. The leg is oriented normal to the removable top. The staple-receiving hole allows a padlock staple access to the padlock and normally traverses through a rear sidewall. The key-receiving track mechanism is mechanically integrated into the bottom.

A tamper-proof padlock box which locks a door to a door frame that ensures that only users with a specialized key can access and open an internal lock. The tamper-proof padlock box includes a guard lock box, a padlock, and a key-receiving track mechanism. The padlock includes a U-shaped shank and a locking body. The guard lock box includes a tubular body, a bottom, a removable top, and a staple-receiving hole. The removable top is slidably mounted to the tubular body and supports the padlock. The U-shaped shank is rotatably mounted to the removable top about a leg of the U-shaped shank. The leg is oriented normal to the removable top. The staple-receiving hole allows a padlock staple access to the padlock and normally traverses through a rear sidewall. The key-receiving track mechanism is mechanically integrated into the bottom.

A security device includes a metallic elongate body with at least one end attachable to a lock unit. The body has at least one track of material of the kind referred to above extending longitudinally on the surface thereof and metallurgically bonded therewith. The material of the track has particles of a hard cut-resistant material dispersed in a self-fluxing matrix of lower melting point than that of the body and comprising one of nickel, iron and cobalt in composition with chromium, silicon and boron. The tracks are normally applied to the elongate body by welding, preferably laser welding or laser cladding, but plasma arc welding or brazing might also be used. The lower melting point prevents melting of the elongate body while enabling the metallurgical bond. Tungsten carbide is the preferred hard cut-resistant material, but other materials might be used, such as silicon carbide, cubic boron nitride, or industrial or synthetic diamond.