B · Si · Ge · As · Sb · Te
Silicon is the clearest everyday example. It behaves neither like a typical metal nor like a typical non-metal, and its semiconductor properties are fundamental to modern electronics and photovoltaic cells.
Boron strengthens some glasses and ceramics. Germanium is used in specialised electronics and optics. Antimony and tellurium appear in alloys and advanced materials. Arsenic has technological uses in some semiconductors but is also well known for its toxicity.
Because 'metalloid' is a descriptive category rather than a rigorously fixed IUPAC group, borderline elements vary between periodic tables. That uncertainty is worth showing rather than hiding.