This template wraps text in <kbd><nowiki>...</nowiki></kbd> markup. To work correctly, it must be substituted.

Markup:

{{subst:kbdnowiki|Some text and a {{convert|179+1/2|ft|1|adj=on|sp=us}} template.}}

Renders as:

Some text and a {{convert|179+1/2|ft|1|adj=on|sp=us}} template.