I’ve been using this and works great so far

CY 90 Degree Right Angled Micro USB 2.0 OTG Host Adapter with USB Power for Galaxy S3 S4 S5 Note2 Note3 Cell Phone & Tablet https://www.amazon.com/dp/B00M7XQ6O2?ref=yo_pop_ma_swf

CY 90 Degree Right Angled Micro USB 2.0 OTG Host Adapter with USB Power for Galaxy S3 S4 S5 Note2 Note3 Cell Phone & Tablet https://www.amazon.com/dp/B00M7XQ6O2/ref=cm_sw_r_cp_api_4tYoBb2S5JQV8

CHENYANG CY 90 Degree Right

• I'm using a Corsair GTX 256GB thumb drive, formatted with ext3.
• For SNES roms I am using Snes9x 2010. Hakchi2 converts the snes roms, I replace these with the original versions directly in the hakchi2 games_snes folder.
• All roms, images, and archives have no spaces and only use alpha-numeric characters.

I have the following emulators working.

• snes9x
• fba/cps2 with neogeo and capcom games
• mame2003
• PCSX ReARMed
• Genesis Plus GX (including sega cd)
• pc engine (including cds)
• pc-fx
• yabause (but it runs horribly)

This is the OTG device I've been using with good success. There's a few others that people are using so there's other options out there:

https://www.amazon.com/gp/product/B00M7XQ6O2/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1