Universal System Single Slotted Standards are counter sunk for a #6 screw. The finish for these standards is Mirror Polished Chrome. 1/2" slots, 1" in on center for 1" adjustments. When to use: The Universal System is recommended for moderate loads and normal traffic conditions. Standards over 6' long will be shipped VIA common carrier. Freight will be quoted separately. You will be notified of the freight amount.