A laser printer is detachably provided with a carrier belt, support rollers for supporting the carrier belt, and a belt unit provided with a belt frame. The ethylene \u03b1-olefin copolymer according to the present invention has a uniform comonomer distribution and exhibits a lower density in the same comonomer content, unlike conventional ethylene copolymers having a random or blocky comonomer distribution. The external connection interface section individually interfaces with the communication sections. Optionally, one or more security andor anti-fraud measures may be implemented, e. An air guide member is mounted inside the housing between the air vents and the fan for guiding air there between. The cutting edge of the first tooth extends all the way to a center axis of the drill; the cutting edges of the second and third teeth have inner ends spaced from the axis to form a space between one another.