Landscaping beds against fence

Installing new landscaping against a back fence and looking for recommendations on what to put between the bed and the fence to prevent the mulch from resting against the fence and causing rot.

It's just going to be a couple inches of dirt and mulch, so not very heavy to where anything significant is required.

Was thinking something like LINK, but like I said it won't be seen its just for a barrier between the dirt/mulch and the fence to prevent fence damage so looking for anything as good or better/cheaper.