I use this in mine https://www.amazon.com/gp/product/B009PYDY5K/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

I ordered 3.5mm and 3mm because I couldn't find for sure what size was needed. I can't remember which one I ended up using. If I still have the bag at home I'll check when I get back this evening. A 5' hose was enough for me to replace all the vacuum connector pieces in my engine bay with a bit left over for later.

__________________
2010 Mercedes E350 4Matic - 77k miles
1986.5 Nissan D21 V6 4x4 - 276k miles
1987 Mercedes 190D 2.5 Turbo - 3??k miles
1983 Mercedes 300SD turbo parts car
2017 Honda CBR500R - 15k miles
2016 Suzuki GSX S1000 - 9k miles