You Do Need power plug adapter while traveling from Eritrea to Switzerland.

Here is Why You Need An Adapter

The outlet and plug type used in Switzerland are C and J and in Eritrea are C and L. This is how they look like.

Eritrea

In Eritrea, outlets of type C and L are in use.

Type C

Type L

Switzerland

In Switzerland, outlets of type C and J are in use.

Type C

Type J