Beseler 23C or 23C serie 2 what this part for

[benjiiiiii]

On the negative stage there is a triangle part, with what seams like two bunny hears.

What is this for ?

Here is a ebay item with a photo of what i'm talking about.

I've checked the manual, It's not that helping

 

[Kino]

Here is a ebay item with a photo of what i'm talking about.

You didn't paste a link...

 

[benjiiiiii]

Sorry for that, here it is
https://www.ebay.ca/itm/Beseler-23C...566359?hash=item521b9c9ad7:g:l-oAAOSw~~9cwzpY

 

[Rick A]

Sliding red filter.

 

[benjiiiiii]

Thanks there is a two images in the manual but in black and white it’s less clear