You can bring a daypack into the cabin as long as it is within the weight limit and size. There is a sizing 'jig' at most airport where if you can put your pack in, then you are okay. Check airline websites to see

About packs. Unfortunately to share with all, there are unethical shops selling replica (fake) Deuter packs at 'real' pack prices. Meaning, even if you pay RM500 for the pack, it may still be a fake. Replica packs are almost 90% copy, the just lack certain 'qualities' which is really hard to differentiate.

I personally would not buy a Deuter in Malaysia. Just too risky and the packs are not all that great either. Many people like it because (unfortunately) its the most easily available pack here.

I strongly recommend you to consider other packs. Brands like Lowe Alpine, Macpac and even Millet makes really good pack. You pay a bit more but some of the models are really good.

Buy pack, buy it once. Make sure the fitting is right and it feels good. Make sure you know how to put it on, test it. Pay a bit more and it will last you a good time. I have seen replica packs fail along a trip. The carrier ends up having to hug and lug the pack around. Not a pretty sight especially if you are in the jungle.

Madam Sia's shop has many brands. WHile Deuter is her major products, she has some Millets and Tatonka I think. Consider these products.

They are a bit like cars. Many people use Proton but that does not mean they are good. They buy it because it is popular and probably what they can afford. If you already have the money to buy a Perdana, why not consider a Toyota, for any model for that matter.

Google and read about the other brands of backpack.

Good luck!