The answer depends on how tall he is already. I am a 5"6 woman and the Teeny Genie is definitely too small for me (sits too high on my back) but the Genie DSL barely fits me and would be too big for anyone shorter so I would not recommend that one. A better alternative would be the Alpinelite 30L pack, which is very similar to the genie DSL but comes in two sizes (Reg and Long). The regular size couls potentially fit a shorter back so I suggest measuring your boy`s back lenght to determine if it will fit him. If not, go with the Teeny genie.
For backpack fitting information, please follow this link: http://tinyurl.com/4og6bup
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