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

Here is Why You Need An Adapter

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

Guyana

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

Type A

Type B

Type D

Type G

Sierra Leone

In Sierra Leone, outlets of type D and G are in use.

Type D

Type G