Half fluff hammy

This is Sergei. He was originally my 6 year old niece's but I've taken him in because he was biting. She was responsible for his care so pretty sure he was ignored and not fed regularly and his cage was sad when I got him, nothing dig in and one little hide. He's seems to really appreciate the improvements having an adult caretaker has brought to him. I ordered him a 12 inch niteangel wheel this morning that I know he is going to love and a new proper cage is next on my list! Instead of hiding he now climbs out of his cage and into my hands. I'm curious though. His middle is grey and super fluffy and his butt is brown and silky. I figured he was a Syrian hamster, but could he be mixed with another kind? It's hard to get a pic cause he's constantly on the run 😅