What is this for?

[nistri]

https://www.holden.co.uk/blog/does-e10-petrol-pose-a-threat-to-classic-cars/?utm_source=Holden+Vintage+%26+Classic+Newsletter&utm_campaign=a1993a4b0a-EMAIL_CAMPAIGN_2021_08_13_08_37_E10&utm_medium=email&utm_term=0_f5aba6e1f8-a1993a4b0a-46158617

old fuel hoses are a fire hazard and will be even more so with new petrol, Andrea

[Wangler]

If anyone wants to use Mikalor clips, this particular version is the best I've found, from racebikebitz on eBay:

"Mikalor Single Ear Plus O Clips 304 Stainless Steel Air Water Hose Pipe Clamps

The Single Ear Plus Clamp is an inexpensive, easy assembly clip which has many applications in addition to its normal role of sealing hoses against loss of liquid, air or gases.

The fact that these clamps are used on very small-bore hoses means that the material of the tube or hose can sometimes be very flexible, making it more difficult to ensure a leak-tight assembly due to the possible deformation of the hose. In these cases, the inner-ring is key in helping to guarantee leak-tightness as well as protecting the hose from being pinched during assembly."

It probably isn't necessary but i've found that a drop of WD40 smeared over the pipe helps to make for a perfect clamp-down.