What's the difference between the Tudor Black Bay 54 and the Black Bay 58? Tudor Black Bay 54 🔷 Smaller case (37 mm) 🔷 Lollipop style seconds hand 🔷 T-fit clasp 🔷 Uses the MT5400 movement Black Bay 58 🔷 Bigger case (39 mm) 🔷 Snowflake style seconds hand 🔷 Original pin micro adjustment in the bracelet 🔷 Uses the MT5402 movement But both are COSC certified movements with 70 hours of power reserve, both are water resistant to 200 meters, and both have the vintage inspired rivet style bracel