End closures for polycarbonate conservatory sheets

[Kric38]

I'm trying to replace conservatory end closures with existing height 30mm as you look at them end on above the guttering. Can buy polycarbonate 25mm, 32mm or 35mm end closures. Anyone tell me which to choose? They have a seal on the underside which lies on top of the sheet to keep water out so I want to have as tight a seal as possible. I'm guessing the 25mm will open wide enough to clamp onto the sheet without breaking.
What do you advise? Cheers.

 

[Mw Roofline]

The 25mm will eventually pop off. You’ll have to use the 32mm ones.