Patent ID: 7041082

Claim:
A cartridge barrel for use in a medication pump comprising: a cylindrical barrel wall comprising an open end and a closed end, wherein the closed end defines an orifice, a cylindrical wall projecting from the closed end of the cylindrical barrel and surrounding the orifice, the end wall comprising an interior face, an exterior face, and axial guides on the exterior face, a tip at the closed end within the end wall and in fluid communication with the orifice, and a ridge defined on an interior face of the barrel wall, wherein the ridge divides the barrel wall into: an open end portion extending from the ridge to the open end, and a closed end portion extending from the ridge to the closed end, wherein the open end portion and the closed end portion do not overlap with the ridge, wherein the open end portion includes only one unbroken, opaque band, wherein the opaque band is more opaque than at least a portion of the open end portion of the barrel wall.