Strong and weak

strong:
1.The only different that you can observe is that the top is a bit dirty with pencil color
2.The bottom of the eraser is really clean and you can not see any color on the eraser.
3.It smells neutral with a touch of plastic and it feels soft and really smooth
4.Additionally you can say that the eraser looks like a little white sponge with many little holes, where some of them are filled with pencil color.
5.Sometimes you can see some black lines from a pencil on it.
weak:
1.When you look at the eraser exactly
2.Some of these holes are filled with color of the pencil
3. The eraser smells like a kind of plastic, but it is not so strong. 
4.You can stretch it really long until it starts to break.
5.There is not a big different between the top of the eraser and the bottom of the eraser, because the shape of the eraser is the same.