This is type I plug adapter. When you take a trip or travel, many countries are where type I sockets can be found. Examples are as follows:

American Samoa / Argentina / Australia / China / El Salvador / Fiji / Guatemala / Kiribati / Nauru / New Zealand / Okinawa / Panama / Papua New Guinea / St. Vincent / Tajikistan / Tonga / Uruguay (Exceptions may occur)

The universal input design can perfectly match with most types of plug except the type M-big South Africa 8.7mm plug. It would be your better choice when your travel appliances have two types of plug. Furthermore, the appropriative pins of plug adapter which can fully match with the wall outlet of your travel destination have better electrical conductivity than universal pins.