There are two 4:1 models suitable for your Cushcraft X-7 beam.
For Yagi Installations
The DXE-BAL200-H10-A often produces results that routinely exceed our customers' expectations. Several Amateurs who have upgraded to a DX Engineering balun reported noticeable improvements in pattern and background noise. This model is built into a folded aluminum enclosure, purposely made with gaps in the case to allow moisture to dry out, designed to handle the abuse of outdoor exposure.
For High-Power Operations
With an over-legal-limit amplifier and RTTY operations, the DXE-BAL200-H11-C is slightly heavier for greater power handling ability and it also offers a noticeable difference in lower received noise and better pattern produced from improved isolation and current balance. It is a sealed balun with a one-time gasket cover, recommended for seaside locations.