This product is described as 'autoclavable for sanitary concerns'!  In other words you can boil them! They are widely used throughout the US correction community.

Here is a size chart but don't please sue us for not being 100% reliable!

               US             UK           EURO

S            5-6              5                39

M           7-8               7               40

L            9-10             9               43

XL         11-12            11             45

2XL       13-14            12             47

3XL       15-16            15             50