This is a spring loaded phone holder designed specifically for use with the Revopoint Inspire tripod. It slides together and the jaws are held closed with a spring. Fits both my iPhone 13 with thin case and Galaxy S23 Ultra with a case. Simply pinch the spring holders from the back to open the jaws and insert your phone.
Included are 2 versions, one designed for heat set inserts, and one with modeled threads (they are intentionally designed to thread in a little tight). There is a small hole in the bottom jaw made for a M2.5 screw. Just install the screw after assembly and it will prevent the jaws from coming fully apart.
The heat set inserts I used: https://www.amazon.com/dp/B08PVQX853?psc=1&ref=ppx_yo2ov_dt_b_product_details
For the top jaw, I use a ¼"-20 grub screw: https://www.amazon.com/dp/B07SK6HVGF?ref=ppx_yo2ov_dt_b_product_details&th=1
The spring I used measures 42mm in length, 9.6mm in diameter, from this spring pack: https://www.amazon.com/gp/product/B00VDRF25C/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1