A gear unit having a housing and a cooling arrangement, wherein a connecting face is arranged on the outside of the gear unit, wherein a cutout which passes through the housing is arranged within the connecting face, wherein the cooling arrangement has tubes, a cover part and an attachment part, wherein the tubes project through the cutout, in particular into the interior region of the gear unit, in particular into the oil sump of the gear unit, wherein the cover part is arranged on the connecting face, in particular wherein a seal, in particular a flat seal, is arranged between the cover part and the connecting face, wherein the attachment part is arranged on that side of the cover part facing away from the connecting face, in particular wherein a further seal, in particular a further flat seal, is arranged between the cover part and the attachment part, wherein the attachment part has on its side facing the cover part two indentations which are spaced apart from each other and in each case form a channel, wherein a first cutout which passes through the attachment part opens into the first of the two channels, which cutout acts as an inlet for a cooling medium, wherein a second cutout which passes through the attachment part opens into the second of the two channels, in particular which cutout acts as an outlet for a cooling medium, characterised in that each of the channels has widened portions (40, 41) which are spaced apart from each other, such that the channel cross-section is not constant, and in that the inlet and the widened portions (40, 41) of the first channel are arranged equidistant from each other in the channel direction, in particular are arranged spaced apart regularly from each other, and in that the outlet and the widened portions (40, 41) of the second channel are arranged equidistant from each other in the channel direction, in particular are arranged spaced apart regularly from each other, and in that the distance of the inlet from the outlet in the channel direction is less than an integral multiple of the distance between the widened portions (40, 41) of the first channel which are next-adjacent to each other, the distance between the two widened portions (40, 41) of the first channel in the channel direction being equal to the distance between the two widened portions (40, 41) of the second channel in the channel direction. wherein a connecting face is arranged on the outside of the gear unit, wherein a cutout which passes through the housing is arranged within the connecting face, wherein the cooling arrangement has tubes, a cover part and an attachment part, wherein the tubes project through the cutout, in particular into the interior region of the gear unit, in particular into the oil sump of the gear unit, wherein the cover part is arranged on the connecting face, in particular wherein a seal, in particular a flat seal, is arranged between the cover part and the connecting face, wherein the attachment part is arranged on that side of the cover part facing away from the connecting face, in particular wherein a further seal, in particular a further flat seal, is arranged between the cover part and the attachment part, wherein the attachment part has on its side facing the cover part two indentations which are spaced apart from each other and in each case form a channel, wherein a first cutout which passes through the attachment part opens into the first of the two channels, which cutout acts as an inlet for a cooling medium, wherein a second cutout which passes through the attachment part opens into the second of the two channels, in particular which cutout acts as an outlet for a cooling medium, characterised in that each of the channels has widened portions (40, 41) which are spaced apart from each other, such that the channel cross-section is not constant, and in that the inlet and the widened portions (40, 41) of the first channel are arranged equidistant from each other in the channel direction, in particular are arranged spaced apart regularly from each other, and in that the outlet and the widened portions (40, 41) of the second channel are arranged equidistant from each other in the channel direction, in particular are arranged spaced apart regularly from each other, and in that the distance of the inlet from the outlet in the channel direction is less than an integral multiple of the distance between the widened portions (40, 41) of the first channel which are next-adjacent to each other, the distance between the two widened portions (40, 41) of the first channel in the channel direction being equal to the distance between the two widened portions (40, 41) of the second channel in the channel direction.