Rod coupler comprising a first clamping jaw, a second clamping jaw, and locking means (63,64) for locking said clamping jaws (10,40) against one another, wherein each clamping jaw (10,40) comprises an outside surface (21,41) and a clamping surface (22,42), wherein each clamping surface (22,42) provides at least two straight grooves (25,26,45,46), each groove (25,26,45,46) running laterally from a different part of the outside surface (21,41) extending into the rod coupler, wherein longitudinal axes (A,B and C,D) of a first groove (25 and 45) and a second groove (26 and 46) of said grooves (25,26,45,46) on one clamping surface (22,42) include an angle (a) that is equal to or less than 160 degrees, wherein said grooves (25,26,45,46) are positioned on the clamping surfaces (22,42) such that, when the clamping jaws (10, 40) face one another with their clamping surfaces (22,42) in locking position, at least the first and the second groove (25,26) of the at least two grooves (25,26) of the first clamping jaw face each a groove (45,46) of the second clamping jaw, wherein opposing grooves (25,46 and 26,45) form an aperture (55,56), wherein each of the at least two apertures (55,56) extends laterally from the outside surface (21,41) of said clamping jaws (10,40) into the rod coupler and is adapted for receiving a rod (4,5) when the locking means (63,64) is released, and wherein the clamping jaws (10,40) locked by the locking means (63,64) clamp the rods (4,5) received in said apertures (55,56), and characterized in that each clamping jaw (10,40) comprises at least one further recess (23,43) from the outside surface (21,41) to the clamping surface (22,42), wherein said at least one further recesses (23, 43) form a through-opening through the rod coupler when the clamping jaws (10, 40) are in locking position, wherein the further recesses (23,43) provide hand gripping portions, the hand gripping portions facilitating the handling of the rod coupler. wherein each clamping jaw (10,40) comprises an outside surface (21,41) and a clamping surface (22,42), wherein each clamping surface (22,42) provides at least two straight grooves (25,26,45,46), each groove (25,26,45,46) running laterally from a different part of the outside surface (21,41) extending into the rod coupler, wherein longitudinal axes (A,B and C,D) of a first groove (25 and 45) and a second groove (26 and 46) of said grooves (25,26,45,46) on one clamping surface (22,42) include an angle (a) that is equal to or less than 160 degrees, wherein each clamping surface (22,42) provides at least two straight grooves (25,26,45,46), each groove (25,26,45,46) running laterally from a different part of the outside surface (21,41) extending into the rod coupler, wherein longitudinal axes (A,B and C,D) of a first groove (25 and 45) and a second groove (26 and 46) of said grooves (25,26,45,46) on one clamping surface (22,42) include an angle (a) that is equal to or less than 160 degrees, wherein said grooves (25,26,45,46) are positioned on the clamping surfaces (22,42) such that, when the clamping jaws (10, 40) face one another with their clamping surfaces (22,42) in locking position, at least the first and the second groove (25,26) of the at least two grooves (25,26) of the first clamping jaw face each a groove (45,46) of the second clamping jaw, wherein opposing grooves (25,46 and 26,45) form an aperture (55,56), wherein each of the at least two apertures (55,56) extends laterally from the outside surface (21,41) of said clamping jaws (10,40) into the rod coupler and is adapted for receiving a rod (4,5) when the locking means (63,64) is released, and wherein the clamping jaws (10,40) locked by the locking means (63,64) clamp the rods (4,5) received in said apertures (55,56), and