A padlock operable at least in a locked mode and an opened mode, comprising: a lock body comprising a first surface and a second surface, a short-leg locking hole and a long-leg locking channel made on the first surface into part of the lock body, and a spindle channel extending from the first surface to the second surface; a shackle locatable in a first shackle position when the padlock is operated in the locked mode, and in a second shackle position when the padlock is operated in the opened mode, the shackle having a short leg, a long leg, a first bolt groove formed on the short leg and a second bolt groove formed on the long leg, the long leg arranged for placement in the long-leg locking channel, the short leg arranged to engage with the short-leg locking hole when the shackle is in the first shackle position, and to disengage from the short-leg locking hole when the shackle is in the second shackle position; a first bolt arranged to engage the first bolt groove inside the lock body; a second bolt arranged to engage the second bolt groove inside the lock body; a spindle dimensioned for placement in the spindle channel, the spindle having a locking area adjacent to the first surface of the lock body, a clutch-mounting portion, and an unlocking groove located between the locking area and clutch-mounting portion, the spindle locatable in a first spindle position and a second spindle position; a plurality of clutches rotatably mounted on the clutch-mounting portion of the spindle; a plurality of dials positioned in relationship to the plurality of clutches so as to lock the spindle in the first spindle position or to allow the spindle to move in a first direction from the first spindle position to the second spindle position, wherein when the spindle is in the first spindle position, the spindle is substantially located within the spindle channel such that the locking area of the spindle is arranged to engage the first bolt with the first bolt groove and to engage the second bolt with the second bolt groove so as to secure the shackle in the first shackle position; when the spindle is in the second spindle position, a portion of the spindle is located outside the spindle channel such that the locking area of the spindle is spaced from the first bolt and the second bolt, allowing the first bolt to move away from the first bolt groove toward the unlocking groove and the second bolt to move away from the second bolt groove toward the unlocking groove so as to allow the shackle to move from the first shackle position to the second shackle position; and when the spindle is in the second spindle position, the spindle can be caused to rotate relative to the lock body for setting a new combination code. a lock body comprising a first surface and a second surface, a short-leg locking hole and a long-leg locking channel made on the first surface into part of the lock body, and a spindle channel extending from the first surface to the second surface; a shackle locatable in a first shackle position when the padlock is operated in the locked mode, and in a second shackle position when the padlock is operated in the opened mode, the shackle having a short leg, a long leg, a first bolt groove formed on the short leg and a second bolt groove formed on the long leg, the long leg arranged for placement in the long-leg locking channel, the short leg arranged to engage with the short-leg locking hole when the shackle is in the first shackle position, and to disengage from the short-leg locking hole when the shackle is in the second shackle position; a first bolt arranged to engage the first bolt groove inside the lock body; a second bolt arranged to engage the second bolt groove inside the lock body; a spindle dimensioned for placement in the spindle channel, the spindle having a locking area adjacent to the first surface of the lock body, a clutch-mounting portion, and an unlocking groove located between the locking area and clutch-mounting portion, the spindle locatable in a first spindle position and a second spindle position; a plurality of clutches rotatably mounted on the clutch-mounting portion of the spindle; a plurality of dials positioned in relationship to the plurality of clutches so as to lock the spindle in the first spindle position or to allow the spindle to move in a first direction from the first spindle position to the second spindle position, wherein when the spindle is in the first spindle position, the spindle is substantially located within the spindle channel such that the locking area of the spindle is arranged to engage the first bolt with the first bolt groove and to engage the second bolt with the second bolt groove so as to secure the shackle in the first shackle position; when the spindle is in the second spindle position, a portion of the spindle is located outside the spindle channel such that the locking area of the spindle is spaced from the first bolt and the second bolt, allowing the first bolt to move away from the first bolt groove toward the unlocking groove and the second bolt to move away from the second bolt groove toward the unlocking groove so as to allow the shackle to move from the first shackle position to the second shackle position; and when the spindle is in the second spindle position, the spindle can be caused to rotate relative to the lock body for setting a new combination code.