Seat back o-rings again

I am redoing the seats on my series 2 and bought an 40 o-ring kit from the usuals. I figured after 40 years it was time to replace the o-rings. The new ones are much smaller in cross section and actually longer than the old ones. WTF! So, I put on my engineer cap and start researching on the internet. I estimate the original ones when new (and not stretched out) were 5/16" in cross section and 2" ID. EPDM rubber is a good weather resistant choice. A metric 8mm cross section o-ring will also work.
I have requested a quote from 1 vendor for 8x54mm EPDM o-rings. I will let you know what I find out. Does anyone have a source for the correct rings?

Here are some from one of the usual providers of Jag Etype spare parts.

Here is one from the UK
Here is another from the USA

Thanks for the links. I am in the USA. The XKS has no dimensions, I can’t call them because of covid-19… the bassetts at least have a ruler in the photo so I can scale and measure. They also seem larger that the old ones. I may just keep the old ones, but will keep searching.

That proves that little to no effort goes into research for the correct parts. O-rings come in nearly every size and the correct ones are available from kit suppliers in the know. Not even the effort to buy a bag to measure them.

An update. My old seat O-rings were OK except for being stretched out after 40 years.
I used 1/2" blunt end hog rings to take a tuck out of each O-ring. Then added some marine grade 3/8" shock cord just for good measure. Attached the cord with 3/8" hog rings. The trick tomorrow will be to get the rough horse hair padding squeezed into the new covers. I tried the covers over the seat backs without the horse hair installed and it was a struggle. I will probably vacuum bag it. What I can’t find out is it OK to leave the bag trapped in there when done?

I wouldn’t think so - you want everything to breathe plus there may be a noise from the bag being crinkled when the seat is in use.

I used foam instead of horsehair and it was a very tight fit but the bag came out okay (in pieces of course).

I thought I remember someone mentioning that Hoover upright vacuum bands could be used on seat backs?

Vacuum belts would work great if you could find them small enough. I actually tried one but decided not to go that route. After what I have done my seat backs are quite firm. We have yet to install them in the car.

Bag is easy to tear out. Before you finish stapling the bottom shut

One of these sizes must work.

I’ve no idea what their pricing is.

The problem with O-rings is most are designed for oil and will not hold up to the ozone in the atmosphere. EPDM is the material choice for the seat rings. By my estimate they need to be 5/16 or 8 mm thick. When I called a similar company they could supply only eight and a set up charge for the next 32 would’ve been thousands of dollars. Seats are all done now so I’ll see how it goes.

They have EPDM. ………