Read the following text and answer the question.

Source: swissgear.com

Everyone must have their favorite thing. Mine is my school bag. I bring it to school every day. I've been using it for more than three years. It is just an ordinary backpack.

The color of my bag is predominantly black but it has a red accent on the front part. It has two straps on the back and a handle on the top of it. The bag has many compartments to put things in. The inside part consists of two sections. One section, the smaller one, at the back is for keeping my laptop. The other section is larger for keeping my school books. Sometimes, I also bring my Harry Potter book in it, so I can read it when I feel bored at school. There is a keychain with my name -- Anna Smith -- on its zipper. In the front part, there is one pocket where I usually put my other stationery in. There is a pocket on the lower part of both sides. I used to put my drink bottle there before both of them broke. I have to get them repaired at the bag reparation shop before I can put my drink bottle in that pocket again.

I really love my bag since it is very useful to me. It might be my last school bag before I graduate from junior high school.

One sentence in the second paragraph is different from the other parts of the paragraph. The description contained in that paragraph does not change if this sentence were omitted. Which sentence is this?