500mm f4 IS 52 mm drop in filter

When cleaning my lens lately, I removed the 52 mm drop in filter holder to be able to clean the UV-filter.
I didn't pay attention, and when I wanted to put it in place again, I realised I forgot in which direction it was originally mounted. There are no markings or arrows that indicate it.
Does it make any diffrence; or has it anny affect on IQ or AF if placed in either direction ? Any trick to be able to put it in again like it was ?

Kind regards,
Wim.

Don't know if it makes a difference which way round it goes but on mine the side with the "Canon Gelatin" text faces the lens hood end i.e. if you lift the filter out and look towards the camera you can read the "Canon Gelatin" wording.

Neil

Thanks Neil !

Kind regards,
Wim

I don't think there is any difference.
I am changing drop-in filter quite often without any probs.