Wrist size. Silicone for fenix 6 band fits wrist 6.89"-9.05" (175mm-230mm), flexible to adjust the length. Duarble silicone watch band for fenix 6. Soft silicone band for 22mm fenix 6 pro, comfortable for daily use. Screw bar clasp. We use screw bar clasp to connect the silicone part, it's more durable to hold the watch band in your wrist. Compatible models:Approach S60/S62/S62 Bundle/S70-47mm,D2 Delta/Mach 1,Descent G1,Descent G1 Solar,epiX (Gen 2),fenix 5/5 Plus/6/6-Pro Solar Edition/7–Sapphire Solar Edition/7-Solar Edition/7-Standard Edition,Forerunner 745/935/945/945 LTE/955/955 Solar/965,Descent G1,quatix 7-Sapphire Edition,MARQ Captain,Descent G1 Solar,MARQ Adventurer,MARQ Athlete,Instinct 2-Camo Edition,D2 Mach 1.