-Any BCI or BCC locality... if you do not try to powerfeed or overfeed you can curb its size below 10' feet.
-Any type of Rainbow - Brazilian's are the best looking and most will range between 4-7 feet
-Ball Pythons - Adults are 4-6 feet and these have great temperaments and are very easy to care for and cheap (personal recommendation)
-Jungle Carpet pythons
-Dumeril's boa
these are the common boas/pythons between 4-10'. Any snake can be restricted in growth by slowing its feeding schedule at the healthy adult size you would like to maintain (I'm not saying to starve your animals to keep them small).
Good luck and let us know what in particular you want this animal for.
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-Iman
1.1 Sugar Gliders (Gizmo and Nema)
1.0 Ball Pythons (Spot)
0.1 Guyanan BCC (TBA)
0.1 Brazilian Rainbow (TBA)
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