A network interface connector, comprising: - an outer housing; and - a contact assembly situated in said outer housing, said contact assembly including - a mounting block, - a first group of first elongate contacts (302, 304, 306, 308) mounted on said mounting block, said first elongate contacts (302, 304, 306, 308) each having a contact portion (a) and a rearward portion (b), - a second group of second elongate contacts (401, 403, 405, 407) mounted on said mounting block, said second elongate contacts each having a contact portion (a) and a rearward portion (c), - said first (302, 304, 306, 308) and second elongate contacts configured such that said contact portions of said first (302, 304, 306, 308) and second (401, 403, 405, 407) elongate contacts are coplanar and such that said rearward portions of said first (302, 304, 306, 308) and second (401, 403, 405, 407) elongate contacts are situated in first and second parallel spaced planes (30, 40) respectively to define a proximity gap between them, and - a proximity insert situated in said proximity gap between said rearward portions of said first (302, 304, 306, 308) and second (401, 403, 405, 407) contacts, said proximity insert having desired electrical characteristics which provide the connector with desired transmission properties, wherein said proximity insert is removably situated in said proximity gap such that said proximity insert is removable from said proximity gap and replaceable by another proximity insert having different electrical characteristics to provide the connector with different transmission properties, characterized in that said proximity insert is removable from said proximity gap after the connector has been soldered to a motherboard and replaceable by another proximity insert without de-soldering the connector, and wherein a pair of slots are formed in opposed sides of said mounting block in alignment with said proximity gap, said slots configured to enable said proximity insert to pass therethrough. - an outer housing; and - a contact assembly situated in said outer housing, said contact assembly including - a mounting block, - a first group of first elongate contacts (302, 304, 306, 308) mounted on said mounting block, said first elongate contacts (302, 304, 306, 308) each having a contact portion (a) and a rearward portion (b), - a second group of second elongate contacts (401, 403, 405, 407) mounted on said mounting block, said second elongate contacts each having a contact portion (a) and a rearward portion (c), - said first (302, 304, 306, 308) and second elongate contacts configured such that said contact portions of said first (302, 304, 306, 308) and second (401, 403, 405, 407) elongate contacts are coplanar and such that said rearward portions of said first (302, 304, 306, 308) and second (401, 403, 405, 407) elongate contacts are situated in first and second parallel spaced planes (30, 40) respectively to define a proximity gap between them, and - a proximity insert situated in said proximity gap between said rearward portions of said first (302, 304, 306, 308) and second (401, 403, 405, 407) contacts, said proximity insert having desired electrical characteristics which provide the connector with desired transmission properties, - a mounting block, - a first group of first elongate contacts (302, 304, 306, 308) mounted on said mounting block, said first elongate contacts (302, 304, 306, 308) each having a contact portion (a) and a rearward portion (b), - a second group of second elongate contacts (401, 403, 405, 407) mounted on said mounting block, said second elongate contacts each having a contact portion (a) and a rearward portion (c), - said first (302, 304, 306, 308) and second elongate contacts configured such that said contact portions of said first (302, 304, 306, 308) and second (401, 403, 405, 407) elongate contacts are coplanar and such that said rearward portions of said first (302, 304, 306, 308) and second (401, 403, 405, 407) elongate contacts are situated in first and second parallel spaced planes (30, 40) respectively to define a proximity gap between them, and - a proximity insert situated in said proximity gap between said rearward portions of said first (302, 304, 306, 308) and second (401, 403, 405, 407) contacts, said proximity insert having desired electrical characteristics which provide the connector with desired transmission properties,