12 include a male formation which defines a spigot 30 the spigot 30 is pivotally secured to the tablet unit 12 for example using a transverse pivot pin not shown and may be operated to articulate between a stowed position in which it is completely within the housing or enclosure of the tablet unit 12 see fig4 a and an extended position in which it protrudes from the housing as is shown in fig4 b as can be seen from fig3 a of the drawings the spigot 30 includes a thin neck region 32 and an enlarged head 34 in order to receive the spigot 30 the base unit 14 includes a complementary female formation shaped and dimensioned to receive the spigot 30 in snug fit therein as will be seen from fig5 a of the drawings in one embodiment the base unit 14 includes a plurality of female formations 36 disposed along the longitudinal axis each of the female formations 36 may be selectively engaged by a spigot 30 to secure the tablet unit 12 when in the laptop mode configuration it will be appreciated that the plurality of female formations 36 allows for selection of different viewing angles fig5 b of the drawings shows one of the female formations 36 of the fig5 a in greater detail as will be seen the female formation 36 includes two sliding members 40 which are mounted within a recess in the base unit 14 to define a transverse slot 42 within which the spigot 30 is receivable the sliding members 40 are biased under the influence of a biasing element to close the transverse slot 42 therebetween in one embodiment the biasing element may include a coil.