An enclosure comprising: a housing including a gel-block mounting sleeve; a gel sealing unit (38, 1038) including: a gel sealing block that mounts within the gel-block mounting sleeve; and an actuator adapted to apply compressive load to the gel sealing block during sealing, and adapted to apply tensile load to the gel sealing block to cause the gel sealing block to radially constrict such that adhesion between an outer surface of the gel sealing block and an inner surface of the gel-block mounting sleeve is broken or weakened; wherein the actuator includes at least one spring for applying the compressive load to the gel sealing block in the form of compressive spring pressure, wherein the actuator includes pressurization structures between which the gel sealing block mounts, wherein the gel sealing block is pressurized between the pressurization structures during sealing, wherein the gel sealing block is coupled to the pressurization structures by a coupling interface that allows the pressurization structures to apply tension to the gel sealing block prior to removal of the gel sealing block from the gel-block mounting sleeve, and wherein during tensioning positioning of the pressurization structures is absolutely controlled by a trigger arrangement of the actuator without influence from the at least one spring. a housing including a gel-block mounting sleeve; a gel sealing unit (38, 1038) including: a gel sealing block that mounts within the gel-block mounting sleeve; and an actuator adapted to apply compressive load to the gel sealing block during sealing, and adapted to apply tensile load to the gel sealing block to cause the gel sealing block to radially constrict such that adhesion between an outer surface of the gel sealing block and an inner surface of the gel-block mounting sleeve is broken or weakened; wherein the actuator includes at least one spring for applying the compressive load to the gel sealing block in the form of compressive spring pressure, wherein the actuator includes pressurization structures between which the gel sealing block mounts, wherein the gel sealing block is pressurized between the pressurization structures during sealing, wherein the gel sealing block is coupled to the pressurization structures by a coupling interface that allows the pressurization structures to apply tension to the gel sealing block prior to removal of the gel sealing block from the gel-block mounting sleeve, and wherein during tensioning positioning of the pressurization structures is absolutely controlled by a trigger arrangement of the actuator without influence from the at least one spring. a gel sealing block that mounts within the gel-block mounting sleeve; and an actuator adapted to apply compressive load to the gel sealing block during sealing, and adapted to apply tensile load to the gel sealing block to cause the gel sealing block to radially constrict such that adhesion between an outer surface of the gel sealing block and an inner surface of the gel-block mounting sleeve is broken or weakened; wherein the actuator includes at least one spring for applying the compressive load to the gel sealing block in the form of compressive spring pressure, wherein the actuator includes pressurization structures between which the gel sealing block mounts, wherein the gel sealing block is pressurized between the pressurization structures during sealing, wherein the gel sealing block is coupled to the pressurization structures by a coupling interface that allows the pressurization structures to apply tension to the gel sealing block prior to removal of the gel sealing block from the gel-block mounting sleeve, and wherein during tensioning positioning of the pressurization structures is absolutely controlled by a trigger arrangement of the actuator without influence from the at least one spring.