A medical device comprising: a core circuitry assembly ; and a core assembly housing configured to enclose the core circuitry assembly , the core assembly housing comprising: a first portion comprising: a first side wall , the first side wall comprising first and second ends ; a first lower wall coupled to the first side wall by a first curved corner portion and extending in a direction away from the inside surface of the first side wall ; and a first upper wall coupled to the first side wall by a second curved corner portion and extending in a direction away from the inside surface of the first side wall ; and a second portion configured to be coupled to the first portion along a weld seam , the second portion comprising a second side wall , the second wall comprising first and second ends ; a second lower wall coupled to the second side wall by a third curved corner portion and extending in a direction away from the inside surface of the second side wall ; and a second upper wall coupled to the side wall by a second curved corner portion and extending in a direction away from the inside surface of the second side wall . and at least one weld joint feature, wherein the at least one weld joint feature includes a thinned section of the second portion , characterised in that notches are defined in said first and second ends extending from an inside surface to an outside surface of said first and second side walls . a core circuitry assembly ; and a core assembly housing configured to enclose the core circuitry assembly , the core assembly housing comprising: a first portion comprising: a first side wall , the first side wall comprising first and second ends ; a first lower wall coupled to the first side wall by a first curved corner portion and extending in a direction away from the inside surface of the first side wall ; and a first upper wall coupled to the first side wall by a second curved corner portion and extending in a direction away from the inside surface of the first side wall ; and a second portion configured to be coupled to the first portion along a weld seam , the second portion comprising a second side wall , the second wall comprising first and second ends ; a second lower wall coupled to the second side wall by a third curved corner portion and extending in a direction away from the inside surface of the second side wall ; and a second upper wall coupled to the side wall by a second curved corner portion and extending in a direction away from the inside surface of the second side wall . and at least one weld joint feature, wherein the at least one weld joint feature includes a thinned section of the second portion , a first side wall , the first side wall comprising first and second ends ; a first lower wall coupled to the first side wall by a first curved corner portion and extending in a direction away from the inside surface of the first side wall ; and a first upper wall coupled to the first side wall by a second curved corner portion and extending in a direction away from the inside surface of the first side wall ; and a second portion configured to be coupled to the first portion along a weld seam , the second portion comprising a second side wall , the second wall comprising first and second ends ; a second lower wall coupled to the second side wall by a third curved corner portion and extending in a direction away from the inside surface of the second side wall ; and a second upper wall coupled to the side wall by a second curved corner portion and extending in a direction away from the inside surface of the second side wall . and at least one weld joint feature, wherein the at least one weld joint feature includes a thinned section of the second portion , <EOS>