Abstract: An interlock arrangement for two slide switches in a radio pager eliminates incorrect switch operation. The casing contains two switches (A and B) with respective switch members (15, 16) located inside the casing. Switch member (15) has a cam follower (15b) on a resilient arm which co-operates with one or the other of two indents (13, 14). Switch member (16) has a chamfered end (16a). The chamfered end (16a) and the cam follower (15b) are shaped so that when switch member (15) is in position 1, the other switch member (16) locks switch member (15). If switch member (15) is inadvertently operated toward position 2, the chamfered end (16a) of switch member (16) will abut against the undersurface of the resilient arm cam follower (15b) thereby forcing the cam follower into more positive engagement with indent (13). Each switch (A or B) has two positions. In order for the interlock arrangement to be effective, each switch member must be located in the same position, for example position 1 or position 2.