This flashcart for 3DS made by Sky3DS supports firmwares up to 9.4.0-21 and therefore works with 3DS XL, 2DS and New 3DS. It might be possible to boot homebrew thanks to smealum and his NINJHAX exploit. It can play 3DS games but is region-locked.

Features List

Supports any 3DS firmware up to 9.4.0-21.
Plays 3DS ROMs
Support all New3DS/3DSLL, 3DS/XL, 2DS consoles(US,EU,JP).
Region-locked
Support eShop and online game.
Compatible with any MicroSD 2GB,4GB,8GB,16GB,32GB,64GB,128GB SDHC/SDXC card.
Requires special software to write to SD Card
Version A has red button, limited to 10 games
Version B has blue button, can play unlimited games
Does not use emunand

Clones

Sky3DS
	Sky3DS
Manufacturer	SKY3DS Team
Firmware Support	Up to 9.5
New 3ds Support	Yes
Is A Clone	No
Has Clone(s)	Yes
SD Support	SDXC up to 128gb
Has LED	Yes
Has USB port	No
Has Button	Yes
Uses Exploit	No
emuNAND Support	No
CIA Support	No
Game Limit	On Some Cards
Region Free	No
GBAtemp's Review	Here
Official Website	sky3ds.com

This cart is a clone: No.
This cart has clone(s): Yes (K3DS, R5 and QQ3DS)

Revisions

Red button card: Has 10 game limit that can be bypassed to 100 games
Blue button card: no game limit

Region Free

Region free using smealum's regionthree on firmwares <9.4.0.

Game Limit

10 game limit on cards with red button, this was bypassed to 100 games.

Images

Cartridge from homepage

Sky3DS