Clockwork Synergy - 26mm 2 Piece Classic Nato PVD Nylon Black/Grey Replacement Watch Strap Band

It's not a "through the pin" strap design but on the Garmin Fenix 3 series (or 5x) you don't need that since the pins are SCREWED in and if they fail you have bigger problems..... On the 3HR or 5X a 2-piece is required so the HR sensor can work, of course.