A compressor comprising: - a cylinder body defining an outer wall having an inner body surface and an outer body surface opposite the inner body surface, wherein the inner body surface partially defines a cylinder chamber, and the cylinder body defines a first end and an open second end opposite the first end; - a cylinder head supported by the cylinder body at the second end, the cylinder head defining an inner head surface that faces the cylinder chamber, an outer head surface that is opposite the inner head surface along a central head axis, and a side wall configured to attach to the cylinder body, wherein the outer head surface defines a concavity along at least one direction; and - a piston supported in the cylinder chamber and movable along a longitudinal direction along an intake stroke that creates negative pressure in the cylinder chamber so as to draw fluid into the cylinder chamber through an inlet, and a discharge that creates positive pressure in the cylinder chamber so as to force fluid out of the cylinder chamber through an outlet, wherein at least one of the inlet and the outlet is defined by the cylinder head, characterized in that, the cylinder head comprises a polymer, the polymer further comprises glass particles embedded therein, and the cylinder head is monolithic; wherein the concavity extends through a plane that is normal to the longitudinal direction and that intersects the outer head surface such that first portion of the outer head surface lies on one side of the plane, and a second portion of the outer head surface lies on an opposite side of the plane, wherein the concavity has a width along the plane, along a first direction perpendicular to the longitudinal direction, wherein the width is at least half of an outer dimension of the cylinder head that extends parallel the width, the outer dimension of the cylinder head extending from a first side wall of the cylinder head to a second side wall of the cylinder head opposite the first side wall, intersecting the central head axis, and wherein the cylinder head deflects less than conventional cylinder heads that do not include the concavity. - a cylinder body defining an outer wall having an inner body surface and an outer body surface opposite the inner body surface, wherein the inner body surface partially defines a cylinder chamber, and the cylinder body defines a first end and an open second end opposite the first end; - a cylinder head supported by the cylinder body at the second end, the cylinder head defining an inner head surface that faces the cylinder chamber, an outer head surface that is opposite the inner head surface along a central head axis, and a side wall configured to attach to the cylinder body, wherein the outer head surface defines a concavity along at least one direction; and - a piston supported in the cylinder chamber and movable along a longitudinal direction along an intake stroke that creates negative pressure in the cylinder chamber so as to draw fluid into the cylinder chamber through an inlet, and a discharge that creates positive pressure in the cylinder chamber so as to force fluid out of the cylinder chamber through an outlet, wherein at least one of the inlet and the outlet is defined by the cylinder head, characterized in that, the cylinder head comprises a polymer, the polymer further comprises glass particles embedded therein, and the cylinder head is monolithic; wherein the concavity extends through a plane that is normal to the longitudinal direction and that intersects the outer head surface such that first portion of the outer head surface lies on one side of the plane, and a second portion of the outer head surface lies on an opposite side of the plane, wherein the concavity has a width along the plane, along a first direction perpendicular to the longitudinal direction, wherein the width is at least half of an outer dimension of the cylinder head that extends parallel the width, the outer dimension of the cylinder head extending from a first side wall of the cylinder head to a second side wall of the cylinder head opposite the first side wall, intersecting the central head axis, and wherein the cylinder head deflects less than conventional cylinder heads that do not include the concavity.