There is provided a device to be used as a magnet. The device comprises a first member, a second member, and a third member. The first member defines a trench extending along a longitudinal direction. The trench has a top being open. Moreover, the first member comprises a first material being magnetizable. The second member is received in the trench and secured to the first member. The second member comprises a second material being magnetizable. Furthermore, the third member is received in the trench and secured to the first member. The third member comprises a third material being magnetizable. The third member and the second member are disposed side-by-side along the longitudinal direction.