This stainless steel plate spring features a height-adjustable arm and multiple mounting options. It's a sturdy plate spring designed to target fish up to 40kg, like the giant grouper (Epinephelus lanceolatus)! This isn't a spring that uses rebound; it's a heavy-duty rod holder designed to stop the powerful pull of large fish like giant grouper and moroko! It's all stainless steel and handmade, making it unique! It won't budge even if a person hangs on the rod! Thank you for looking.