The rain cap, also known as chinese cap, has as its main purpose prevent entry of rainwater through the chimney. Is the most economic solution.
The interior cone has two functions:
1) Guiding the condensation through the interior of the pipes (keeping the pipes clean)
2) Prevent the accumulation of gases / smoke
Manufactured in Stainless Steel AISI 304, CrNi 18/10, 1st quality, with a thickness 0,5mm, no cutting edges, with silicone o-ring to 250ºC to ensure better tightness / sealing.