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 (248, 250); 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 (270, 272); 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 (278, 280) are defined in said first and second ends (248, 250, 270, 272) extending from an inside surface (234A, 256A) to an outside surface (234B, 256B) 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 (248, 250); 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 (270, 272); 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 (248, 250); 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 (270, 272); 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,