substantially planar barrier sheet the barrier sheet may be encased by breakable separators which cover the cutters to prevent inadvertent injury but expose the cutters when broken upon an attempt to penetrate the barrier the barrier may be retracted into an opening preferably into a concealed compartment application_number US 69296703 A description referring to fig1 9 system 100 comprises cutters 102 and connectors 104 connectors 104 are utilized to connect cutters 102 forming a barrier capable of blocking an opening such as a storefront window or doorway from penetration by various objects such as animals people and weapons as shown in fig4 system 100 may also comprise a separator 106 capable of separating cutters 102 from their surroundings so as to prevent accidental cutting of proximately moving objects system 100 may also comprise a retractor 108 and retraction compartment 110 for moving cutters 102 in and out of the opening preferably cutters 102 are barbs such as those extending from barbed wire or those extending from barbed tape as is known in the art under appropriate circumstances considering issues such as cost manufacturing local laws etc cutters may be fashioned from other materials such as sharpened strips of plastic the cutters are connected to form strips 207 preferably the cutters 102 are integral with the connectors 104 such as the case with barbed wire or barbed tape but the cutters may be connected by separate connectors the preferred distance e between cutters 102 is about 4 inches as shown in fig2 a plurality of strips 207 is connected to each other to form an accordion like barrier sheet preferably the strips 207 are connected to each other utilizing rivets 206 at spaced locations the preferred distance b between rivets 206 is about 8 inches as shown in fig1 under.