What size format for a 105mm lens?

[ymc226]

I use a 50mm enlarger lens for 35mm and 80mm for medium format with Beseler 67 or 23 enlargers. I was organizing my darkroom stuff today and found an El Nikkor 105mm enlarger lens that I got as part of an enlarger package I won at the usual auction site. Can I use this for medium format as well?

 

[Nick Zentena]

6x9 or smaller.

 

[jovo]

I use a 105mm El Nikkor for 6x6 and 6x7 with my Beseler 23CIII. The results are in my gallery here. I've no idea why one needs any other lens for medium format.

 

[ymc226]

Jovo, is your lensboard flat or does it have an extension?