I have the very same Flyback,one of my favorites.I dont know about yours but my rubber strap Is one huge pain In the ass to put back on once It's off. Im not really Into rubber straps that much so It's no big deal really. The rubber strap on mine fits so tight Into the lugs, It like It's spring loaded,very tight. I purchased the carbon fiber strap that go's on the 212,looks real nice on the cf leather strap. Enjoy your 253,It's a real beauty (ps) The gen 253 Is Indeed 44mm and 51 with crown