Super Game Boy game cartridges for Super Famicom?

[dondetti]

I've seen a couple of those and they all seem to be exclusive to the japanese Super Famicom. They seem to be regular games but with a Game Boy cartridge slot on top. What's its use?

For example I was interested in the RPG Tsukuru series and found out the second one has this type:

http://www.ebay.de/itm/RPG-Tsukuru-2-RPG-Maker-SFC-SNES-Super-Famicom-Nintendo-Japan-Import-US-Seller-/161640157153?hash=item25a2810fe1

I know there also was an RPG Tsukuru on Game Boy, so does that mean I need the corresponding Game Boy cart to make this work at all? Or maybe you can get extra stuff by connecting these two versions, like for example Metroid Fusion with Metroid Prime via link? I'd like to know before I jump on to this.

[abe]

They're for memory packs to be used with the Satellaview.

http://satellaview.wikia.com/wiki/Slotted_cartridge

[dondetti]

They're for memory packs to be used with the Satellaview.

http://satellaview.wikia.com/wiki/Slotted_cartridge

Thanks! That's pretty cool actually, never heard about that data broadcast before. So now its only purpose is for data storage unless I'd happen to find a memory pack prefilled with RPG Tsukuru extras.