An indexable and double-sided round cutting insert for a milling tool, the cutting insert comprising: an upper side having an upper flat support surface, a lower side having a lower flat support surface, a center axis of the round cutting insert extending between said upper and lower side (10, 20), a median plane extending perpendicular to said center axis and being situated halfway between the upper and lower side, a side surface extending between said upper and lower side (10, 20), wherein an upper cutting edge is formed between said upper side and said side surface, and a lower cutting edge is formed between said lower side and said side surface, said side surface comprising an upper and a lower positive clearance surface (31, 32) such that said upper positive clearance surface has a substantially frusto-conical extension at an upper positive clearance angle (α) with respect to said upper cutting edge and said lower positive clearance surface has a substantially frusto-conical extension at a lower positive clearance angle (β) with respect to said lower cutting edge, and a plurality of protrusions extending along said side surface and protruding in a radial direction perpendicular to said center axis of the round cutting insert, characterized in that each of said plurality of protrusions comprises an outer surface, which in a direction along said center axis is extending such that a first radial distance from said center axis to said outer surface in the median plane of said insert is greater than a second radial distance from said center axis to said outer surface in parallel planes located closer to said upper or lower side of the round cutting insert. an upper side having an upper flat support surface, a lower side having a lower flat support surface, a center axis of the round cutting insert extending between said upper and lower side (10, 20), a median plane extending perpendicular to said center axis and being situated halfway between the upper and lower side, a side surface extending between said upper and lower side (10, 20), wherein an upper cutting edge is formed between said upper side and said side surface, and a lower cutting edge is formed between said lower side and said side surface, said side surface comprising an upper and a lower positive clearance surface (31, 32) such that said upper positive clearance surface has a substantially frusto-conical extension at an upper positive clearance angle (α) with respect to said upper cutting edge and said lower positive clearance surface has a substantially frusto-conical extension at a lower positive clearance angle (β) with respect to said lower cutting edge, and a plurality of protrusions extending along said side surface and protruding in a radial direction perpendicular to said center axis of the round cutting insert, characterized in that each of said plurality of protrusions comprises an outer surface, which in a direction along said center axis is extending such that a first radial distance from said center axis to said outer surface in the median plane of said insert is greater than a second radial distance from said center axis to said outer surface in parallel planes located closer to said upper or lower side of the round cutting insert.