A worm drive hose clamp with a 9mm wide band and a 10mm to 16mm clamping range. This is the size for the fine plumbing in an engine bay: vacuum and boost reference lines, small breather hoses, washer and low-pressure fuel lines, and the short silicone joins on small-bore alloy pipework. The narrow band suits soft, small-diameter hose that a wider clamp would struggle to seat evenly around. Position the clamp fully over the barb or spigot rather than on the hose alone, and tighten progressively so the band pulls up square. Check the hose outside diameter falls comfortably within the range rather than at the extreme.