A tube retainer comprising: a block comprising: a top wall; a bottom wall; a first side wall; a second side wall; a third side wall; and a fourth side wall; a first opening comprising a tube slot having a first slot end and a second slot end, and a second opening having a generally annular shape, the first opening communicating with the second opening, the first and second openings (151; 152) passing through the top wall and the bottom wall; wherein the third side wall or the fourth side wall includes the first slot end of the tube slot; wherein at least the first side wall and the second side wall each include a male block connector comprising a first extending arm having a free end including a lug facing perpendicularly to the first extending arm and generally parallel to the side wall, and a second extending arm having a free end including a lug facing perpendicularly to the second extending arm and generally parallel to the side wall, wherein the lug on the first ending arm and the lug on the second extending arm face away from each other, the male block connector further comprising an extending tongue between the first extending arm and the second extending arm; and/or a female block connector (190/190') comprising a recess comprising a first lug pocket having an open end and a closed end, and a second lug pocket having an open end and a closed end, wherein the first lug pocket and the second lug pocket are arranged generally parallel to the side wall and the open end of the first lug pocket faces the open end of the second lug pocket, the recess further comprising a central indentation between the first lug pocket and the second lug pocket a top wall; a bottom wall; a first side wall; a second side wall; a third side wall; and a fourth side wall; a first opening comprising a tube slot having a first slot end and a second slot end, and a second opening having a generally annular shape, the first opening communicating with the second opening, the first and second openings (151; 152) passing through the top wall and the bottom wall; wherein the third side wall or the fourth side wall includes the first slot end of the tube slot; wherein at least the first side wall and the second side wall each include a male block connector comprising a first extending arm having a free end including a lug facing perpendicularly to the first extending arm and generally parallel to the side wall, and a second extending arm having a free end including a lug facing perpendicularly to the second extending arm and generally parallel to the side wall, wherein the lug on the first ending arm and the lug on the second extending arm face away from each other, the male block connector further comprising an extending tongue between the first extending arm and the second extending arm; and/or a female block connector (190/190') comprising a recess comprising a first lug pocket having an open end and a closed end, and a second lug pocket having an open end and a closed end, wherein the first lug pocket and the second lug pocket are arranged generally parallel to the side wall and the open end of the first lug pocket faces the open end of the second lug pocket, the recess further comprising a central indentation between the first lug pocket and the second lug pocket a male block connector comprising a first extending arm having a free end including a lug facing perpendicularly to the first extending arm and generally parallel to the side wall, and a second extending arm having a free end including a lug facing perpendicularly to the second extending arm and generally parallel to the side wall, wherein the lug on the first ending arm and the lug on the second extending arm face away from each other, the male block connector further comprising an extending tongue between the first extending arm and the second extending arm; and/or a female block connector (190/190') comprising a recess comprising a first lug pocket having an open end and a closed end, and a second lug pocket having an open end and a closed end, wherein the first lug pocket and the second lug pocket are arranged generally parallel to the side wall and the open end of the first lug pocket faces the open end of the second lug pocket, the recess further comprising a central indentation between the first lug pocket and the second lug pocket