5441 strap size

Could any one tell me what is the strap size for the 5441? Lug is 22mm I think
and the buckle? Thank you

Most IWC straps take an 18mm Tang Buckle, but there are exceptions. There is a
20mm Buckle as well.

I was hoping somebody with 5441 and OEM bracelet can give me an answer, I
think it's 22/16mm?

It's 22/18 mm.