I have been trying to fit a Rollei cap for someone who lives in another state and sent what I thought was the correct size for this 3.5F (I believe it's a 3.5F) I sent a Bayonet II folding cap and the person says it didn't fit. I have a picture that they sent but it is not too clear. Does anyone out there have any ideas? The serial Number is: 1761463 The pic is here: http://tinyurl.com/l84rgv Thanks..Maurice