An injector assembly (100) includes a main body (102) having a first connecting arrangement, and a cap (104) having a second connecting arrangement for, in use, releasably connecting the cap to the first connecting arrangement of the main body. The first or the second connecting arrangement (120) includes an open neck portion (122) leading to a locating portion (124), at least part of the locating portion having a maximum width (120A) greater than a maximum width (120B) of the open neck portion. The second of the first connecting arrangement (108), respectively, includes a head portion (109) having a maximum width (108A) greater than the maximum width of the open neck portion.
