Sorry for abrupt reply earlier, was on my iPhone.
My replies are all based on
Woodlore Epic Twin Tube Shoe Tree as I am partial to it

It should work on the other shoe trees as well, but please verify first
I checked out
Shoes & Handbags - designer shoes, handbags, jewelry, watches, and fashion accessories | endless.com, but how does the size chart work? Not sure which size they are referring to. My shoes are size 41.
Based on the size chart, EU 41 is a US9 size, and you would need either a Medium or Large, depending on the width of your shoe. US EEE Width, or UK G width, you would need a large. Else, get a Medium Width.
Thanks Ind1go for your suggestion.
Do you know how the sizing chart for endless.com works? My shoes are a 8.5-9 (depending on the type). Do you know what size I should take for my shoe trees?
& how much is the estimated shipping as well?
Thanks.
I assume your shoes are a US size, for 8.5 - 9, you would need to get Medium size or Large size. If your shoes are very wide, then get the Large size.
Shipping and handling is very cheap, at US$5 for orders below $100. For orders above USD$100, shipping is free.
Edit: You can also get shoe trees from cobblers, but they usually cost about SGD$60.