Here is a screenshot of this ad unit:
So you can say that this ad unit is simply amazing and best way to boost your Adsense earnings as well as increasing page views. Also after adding this ad unit you can remove your related post widget because it works as related post widget and ad server.
Before showing you how to install this ad unit let me tell you that this ad unit is not available for every Google Adsense user, to know are you eligible for this ad unit go to your Adsense account and create a new ad unit, if matched content ad unit option is there then it means you can use this ad unit.
Eligibility to use Matched content
2. Eligible but can’t show ads yet – Your site have a minimum requirements for traffic volume and number of unique pages but still needs improvement.
3. Eligible and can show ads – Your site have our minimum requirements for traffic volume and number of unique pages, and it can show ads.
Step to check if your site is eligible for Matched content:
1. Go to Google Adsense and login to your account.
2. Go to settings > my sites > Matched content
2. Go to my ads > create ad unit > Matched content ad unit.
Read more about Match content feature at Adsense Help Center