You Do Need power plug adapter while traveling from Namibia to Guyana.

Here is Why You Need An Adapter

The outlet and plug type used in Guyana are A, B, D and G and in Namibia are D and M. This is how they look like.

Namibia

In Namibia, outlets of type D and M are in use.

Type D

Type M

Guyana

In Guyana, outlets of type A, B, D and G are in use.

Type A

Type B

Type D

Type G