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

Here is Why You Need An Adapter

The outlet and plug type used in Egypt are C and F 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

Egypt

In Egypt, outlets of type C and F are in use.

Type C

Type F