Given a first selector: SelectorA, you can find the next match of SelectorB as below:
Example with mouseover to change border-with:
$("SelectorA").on("mouseover", function() {
var i = $(this).find("SelectorB")[0];
$(i).css({"border" : "1px"});
});
}
General use example to change border-with:
var i = $("SelectorA").find("SelectorB")[0];
$(i).css({"border" : "1px"});