I'm doing an EPDM cold roof due to height restrictions and plan on using an abutment vent where it meets a wall on one of the sides. 

is there an off the shelf trim i can buy to act as the flashing like in the image, or what would be my best method method to achieve this? 

is it something that would be made out of lead? sorry for the basic question but roofing is not something ive done much of.

 

The usual folk, Glidevale, Manthorpe et al do these.

ive got some of the soffit ventilators ready to be fitted, but was looking too see if a company did ready made flashing trims. i did look on the glide vale website etc.. but couldn't see owt.