You Do Need power plug adapter while traveling from San Marino 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 San Marino are C, F and L. This is how they look like.

San Marino

In San Marino, outlets of type C, F and L are in use.

Type C

Type F

Type L

Sierra Leone

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

Type D

Type G