100 because the elevating buckle is installed to for example the shoulder strap of the knapsack so as to be vertically moved even in this case the plug member 100 and the socket member 200 may be respectively provided with the first magnet 120 and the second magnet 220 thereby being simply connected to each other by magnetic force when they are simply brought close to each other fig1 illustrates an embodiment in which in addition to fig1 a loop 240 may be formed on one end of the elevating rail holder 230 which is formed on the rear end of the socket member 200 as such a water supply hose which is connected to a water bottle may be connected and fixed to the elevating buckle which is located on the chest region of the knapsack in addition a whistle 130 may be fitted to the crossbar on the rear end of the plug member 100 so as to be carried along with the buckle when the user who wears a knapsack goes climbing or trekking the user may carry a water bottle in the knapsack and may try to drink water through a hose of the water bottle without taking off the knapsack in this case the hose may be held and fixed on the loop 240 which ensures the convenient use of the hose in addition when the whistle 130 is carried by being connected to the rear end of the plug member 100 according to the present invention the whistle 130 may be simply used in an emergency situation when the loop 240 or the.