When designing my Dolphin Striker or Martingale, I wanted to be sure never to harm a dolphin! My machinist said he could make anything I could draw, so the next morning, I brought him my sketch of a dolphin with back arched upwards. He smiled and added 2 of them to each side of my Dolphin Striker as a design element which also captures the side of the 1/2" 1x19 wire used for the bobstay.
The upper end of the striker in my mind, needed to be able to take minor movement. I had seen too many fixed upper ends, that appeared to me to invite failure from fatigue caused by varying side loads.
I designed a pivoting block and Rick Heim machined it out of a solid piece of 316 stainless Steel.