Tuning Available options for externally adjustable in-line bottle regulator

Hey guys, can anyone please advise on available options to add an externally adjustable in-line regulator to a bottle airgun? The only one I found so far is this one: Ninja Flex Adjustable Pressure 1000-3000Psi Air Tank Regulator, which is basically a glorified paintball reg. Costs around $150 here: https://mcsus.com/products/ninja-flex-adjustable-pressure-1000-1700psi-air-tank-regulator. it comes in 3 versions - 1000-1700psi, 1700-2500psi, 2200-3000psi. I'd say for 4500psi rated bottle I need to go for 2200-3000psi one, but I might be wrong. Any other options available out there? I saw a few posts talking about JSAR external regs, but could not find any for sale, probably they are not manufactured any longer. And if you did actually add an external reg like this - how was your experience? Which gun and was it worth it? What are the possible issues that I need to watch for, things to be away, things to do and do not do. Questions, questions. Please advise before I screw this up myself, your experience and expertise are the most valuable assets of this forum . Thanks guys!

EDIT 7/15/2024: Added HUMA external regulator, thank you @Firewalker.
HUMA Externally Adjustable Inline PCP Regulator With Integrated Fillset. Costs 156 euro here https://huma-air.com/externally-adjustable-inline-pcp-regulator-with-integrated-fillset. Pressure stacking: 70-125 bar, 100-200 bar, 180-250 bar. Only one gauge showing output pressure does not have input pressure gauge!