For most items, it's specified in the description what materials they're made from, but sometimes this info is completely missing.

However, the tags that are used to filter results on the sidebar are very incomplete and inaccurate. For instance, if I select only 'long-sleeve shirts', I only see a small number of results - lots of long-sleeve shirts disappear. If I select 'short-sleeve shirts' and unselect 'polo shirts', I still see heaps of polo shirts.

Likewise with materials, if I select 'cotton' and 'linen' and unselect 'synthetic', I still see items made from blended materials.

There are two ways to fix this: either have complete and accurate info for all products using a limited set of tags, so e.g. all shirts are tagged as either 'natural fibres', 'synthetic', or 'blended', OR provide the ability to EXCLUDE certain tags from results, e.g. so I can see all shirts EXCEPT polos.