A side release buckle that closes itself. Bring the two halves near each other and the magnets pull them into alignment, so you can fasten it one-handed, in the dark, or with gloves on, without lining anything up by feel. Release is the same side squeeze you already know. Dual adjust means the webbing runs free on both halves rather than being fixed on one side, so you can set the length from either end. That's what you want when both ends need to move independently, or when the strap is anchored at both ends and you're taking up slack in the middle. If you only need to adjust from one side, the single adjust version is simpler and cheaper. Available in [sizes] to match your webbing, with no minimum order, so you can try one before committing to a run. Product Details Material: Acetal with embedded magnets Colour: Black Sizes: [sizes] Size L (mm) W (mm) H (mm) Weight (g) Tensile Strength (kgf) 38mm 70.4 52..7 11.6 100.45