A pressure actuated cable sealing unit comprising: a plurality of separately identifiable cable sealing modules (33a-33f) that can be independently installed in and independently removed from the cable sealing unit, the cable sealing modules (33a-33f) including at least three cable sealing modules (33a-33f); an actuation arrangement (31, 352, 452) for concurrently pressurizing the cable sealing modules (33a-33f); and peripheries of the cable sealing modules (33a-33f) having outer gel sealing surfaces that contact an interior surface of a housing opening receiving the sealing unit; the cable sealing modules (30, 30a-f) each including volumes of sealant contained between first and second axial containment structures (76, 78), wherein the volumes of sealant of the sealing modules each include at least first and second sealing parts (74a, 74b) that can be separated to allow for lateral cable insertion into the sealing modules (33a-33f), and wherein first and second axial containment structures (76, 78) of the sealing modules (33a-33f) each include first and second containment parts (76a, 76b, 78a, 78b) corresponding to the first and second sealing parts (74a, 74b), wherein the first and second sealing parts (74a, 74b) include first and second half-pieces that together define at least one cable port (30, 30a-f); the at least one cable port extending axially through the volumes of sealant, wherein the first and second axial containment structures (76, 78) interface with first and second pressurization structures (60, 62) of the actuation arrangement (31, 352, 452) such that the first and second pressurization structures (60, 62) apply pressure axially through the first and second axial containment structures (76, 78) to the volumes of sealant when the actuation arrangement (31, 352, 452) is actuated. a plurality of separately identifiable cable sealing modules (33a-33f) that can be independently installed in and independently removed from the cable sealing unit, the cable sealing modules (33a-33f) including at least three cable sealing modules (33a-33f); an actuation arrangement (31, 352, 452) for concurrently pressurizing the cable sealing modules (33a-33f); and peripheries of the cable sealing modules (33a-33f) having outer gel sealing surfaces that contact an interior surface of a housing opening receiving the sealing unit; the cable sealing modules (30, 30a-f) each including volumes of sealant contained between first and second axial containment structures (76, 78), wherein the volumes of sealant of the sealing modules each include at least first and second sealing parts (74a, 74b) that can be separated to allow for lateral cable insertion into the sealing modules (33a-33f), and wherein first and second axial containment structures (76, 78) of the sealing modules (33a-33f) each include first and second containment parts (76a, 76b, 78a, 78b) corresponding to the first and second sealing parts (74a, 74b), wherein the first and second sealing parts (74a, 74b) include first and second half-pieces that together define at least one cable port (30, 30a-f); the at least one cable port extending axially through the volumes of sealant, wherein the first and second axial containment structures (76, 78) interface with first and second pressurization structures (60, 62) of the actuation arrangement (31, 352, 452) such that the first and second pressurization structures (60, 62) apply pressure axially through the first and second axial containment structures (76, 78) to the volumes of sealant when the actuation arrangement (31, 352, 452) is actuated.