The Flip World Add-On retails for US$9.99 (S$14) and it consist of a US/AU Plug add-on and an EU Plug add-on.
After a successful launch of the Flip British Plug on Kickstarter, Oneadaptr announced the Flip World product range in November 2017. They offered a 30% discount for those who pre-order those products with the coupon code, WorldIn18.
Flip World product range has four products under it:
I backed the Flip British Plug on Kickstarter on 22nd November 2015. The project was funded on 18th December 2015 after raising a total of £28,115 out of their initial goal of £15,000 from 1,140 backers.
I chose the £14 reward level and shipping to Singapore cost another £5. So in total, I paid £19 (S$38).