PLEASE, before move the topic to the other forums, let some people reply

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I may look a bit stupid, but have some doubts about the sizes. I have a replica jersey and a swingman jersey (the first one is size L and the other M). My size is something between L and M, but both sizes are ok for me. I am looking for an authentic jersey, and this is my doubt:
If you see the sizing information on the nba official store, they say that the L size for the replica jersey means:
Chest 44
Lenght 33
And the L size of the authentic means:
Chest 48
Lenght 35
So, does it mean that my size for the authentic jerseys is M? If this is true, I'm not going to be able to buy an authentic jersey, because there aren't almost authentic jerseys smaller than 48 on Ebay.
Thanks if you can reply.