You Do Need power plug adapter while traveling from Eritrea to Isle of Man.

Here is Why You Need An Adapter

The outlet and plug type used in Isle of Man are C and G 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

Isle of Man

In Isle of Man, outlets of type C and G are in use.

Type C

Type G