you should not run either for 20 weeks and they are polar opposites.. if you want to gain size, you want rad140... for the best quality sarms visit either https://sarms.forsale or https://umbrellalabs.is
You won't get huge from a single SARMs cycle man. And 20 weeks is too long. If you are set on only a single compound then I would go with LGD at 10mg per day for gaining mass. Run it 12 weeks though and PCT.