A pressure-blocking feedthru comprising: a first pressure-blocking assembly comprising: a first insulated pin assembly, and a first pressure barrier shell that encases the first insulated pin assembly; a second pressure-blocking assembly comprising: a second insulated pin assembly, and a second pressure barrier shell that encases the second insulated pin assembly and that attaches to the first pressure barrier shell; comprising further an interface assembly that couples the first pressure-blocking assembly to the second pressure-blocking assembly and that comprises: a first double-sided sleeve that couples the first insulated pin assembly to the second insulated pin assembly; and a dielectric sleeve that circumscribes the first doubled ended socket and at least part of the first and the second insulated pin assemblies (24, 56), characterized by, an air gap separates an inner surface of the dielectric sleeve and an outer surface of the first double-sided sleeve, wherein the air gap is maintained at atmospheric pressure, and wherein the first pressure-blocking assembly further comprises a first metallic c-seal positioned between the first insulated pin assembly and the first pressure barrier shell, and wherein the second pressure-blocking assembly further comprises a second metallic c-seal positioned between the second insulated pin assembly and second pressure barrier shell. a first pressure-blocking assembly comprising: a first insulated pin assembly, and a first pressure barrier shell that encases the first insulated pin assembly; a second pressure-blocking assembly comprising: a first insulated pin assembly, and a first pressure barrier shell that encases the first insulated pin assembly; a second pressure-blocking assembly comprising: a second insulated pin assembly, and a second pressure barrier shell that encases the second insulated pin assembly and that attaches to the first pressure barrier shell; comprising further an interface assembly that couples the first pressure-blocking assembly to the second pressure-blocking assembly and that comprises: a first double-sided sleeve that couples the first insulated pin assembly to the second insulated pin assembly; and a dielectric sleeve that circumscribes the first doubled ended socket and at least part of the first and the second insulated pin assemblies (24, 56), characterized by, an air gap separates an inner surface of the dielectric sleeve and an outer surface of the first double-sided sleeve, wherein the air gap is maintained at atmospheric pressure, and wherein the first pressure-blocking assembly further comprises a first metallic c-seal positioned between the first insulated pin assembly and the first pressure barrier shell, and wherein the second pressure-blocking assembly further comprises a second metallic c-seal positioned between the second insulated pin assembly and second pressure barrier shell. a first double-sided sleeve that couples the first insulated pin assembly to the second insulated pin assembly; and a dielectric sleeve that circumscribes the first doubled ended socket and at least part of the first and the second insulated pin assemblies (24, 56), characterized by, an air gap separates an inner surface of the dielectric sleeve and an outer surface of the first double-sided sleeve, wherein the air gap is maintained at atmospheric pressure, and wherein the first pressure-blocking assembly further comprises a first metallic c-seal positioned between the first insulated pin assembly and the first pressure barrier shell, and wherein the second pressure-blocking assembly further comprises a second metallic c-seal positioned between the second insulated pin assembly and second pressure barrier shell.