I use this one from Amazon:
https://www.amazon.com/dp/B01M0OX3EW?ref=yo_pop_ma_swf
It serves its purpose and is comfortable, but if you forget to take your ring off when you wash your hands, it gets kinda gross and full of soap.
GWHOLE Ring Size Adjuster with Silver Polishing Cloth,Set of 4 (2mm/3mm) https://www.amazon.com/dp/B01M0OX3EW/ref=cm_sw_r_cp_apa_i_MLScCbAQWW90V I bought these!