An end cap assembly comprising: (a) a first connector element (50A, 50A1) comprising at least two first connector element snap arches, each of the at least two first connector element snap arches including a snap tooth lock; and at least two first connector element snap arms, each of the at least two first connector element snap arms including a snap tooth; the first connector element having a central cavity closed off with a wall or having a central opening (5 1A) with a side wall having an internal thread; wherein the first connector element includes two cylindrical walls (80A, 80A') projecting upwardly from a base, each wall (80A, 80A') having a hyperbolic paraboloid shape with an uppermost part (81A, 81A'), wherein the cylindrical walls (80A, 80A') have uniform acclivity; (b) a second connector element comprising at least two second connector element snap arches, each of the at least two second connector element snap arches including a snap tooth lock; and at least two second connector element snap arms, each of the at least two second connector element snap arms including a snap tooth; the second connector element having a central opening, and an annular channel for receiving an end of a hollow cylindrical filter element; wherein the second connector element includes two cylindrical walls (80B, 80B') projecting upwardly from a base, each wall (80B, 80B') having a hyperbolic paraboloid shape with an uppermost part (81B, 81B'), wherein the cylindrical walls (80B, 80B') have uniform acclivity; and, (c) a gasket arranged between the first connector element and the second connector element, the gasket having a central opening); wherein the first connector element and the second connector element are lockably engageable with each other when placed in contact with each other and axial force is applied such that each first connector element snap tooth is retained in each respective second connector element snap tooth lock, and each second connector element snap tooth is retained in each respective first connector element snap tooth lock. (a) a first connector element (50A, 50A1) comprising at least two first connector element snap arches, each of the at least two first connector element snap arches including a snap tooth lock; and at least two first connector element snap arms, each of the at least two first connector element snap arms including a snap tooth; the first connector element having a central cavity closed off with a wall or having a central opening (5 1A) with a side wall having an internal thread; wherein the first connector element includes two cylindrical walls (80A, 80A') projecting upwardly from a base, each wall (80A, 80A') having a hyperbolic paraboloid shape with an uppermost part (81A, 81A'), wherein the cylindrical walls (80A, 80A') have uniform acclivity; (b) a second connector element comprising at least two second connector element snap arches, each of the at least two second connector element snap arches including a snap tooth lock; and at least two second connector element snap arms, each of the at least two second connector element snap arms including a snap tooth; the second connector element having a central opening, and an annular channel for receiving an end of a hollow cylindrical filter element; wherein the second connector element includes two cylindrical walls (80B, 80B') projecting upwardly from a base, each wall (80B, 80B') having a hyperbolic paraboloid shape with an uppermost part (81B, 81B'), wherein the cylindrical walls (80B, 80B') have uniform acclivity; and, (c) a gasket arranged between the first connector element and the second connector element, the gasket having a central opening);