Washable Colouring Book

We bought for Hui and Xuan a washable colouring book set each when we were at Jusco shopping last Saturday. Each set come with a 4 pages colouring book and 3 bath crayons. They have been enjoying colouring the 4 cute girls since then. Then, they will bring to the bath room to wash away the colours during bathing time. After that, they can start to colour the cute girls again. One minus point, the shop don't seem to sell additional colours bath crayons. Thus, the girls can only colour the pictures with pink, purple and yellow which seems a bit dull after sometime.