This is used to lock the RTL-SDR V-dipole into a optimal 120 degree angle.
The files come with or without a compass mount to orient the antenna north-south. Additionally, if a reflector is wanted, there is an additional 120 degree guide that fits 1/4" metal rods and clips onto 2" PVC.
The RTL-SDR V-Dipole can be found here: https://www.rtl-sdr.com/using-our-new-dipole-antenna-kit/
An appropriate flatpack compass can be found here: https://www.amazon.com/gp/product/B07FXH2CPT/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=w2bro-20&creative=9325&linkCode=as2&creativeASIN=B07FXH2CPT&linkId=ca1e093b76360bde601b0dae962fb0b8