Which type of nails is larger than 20-penny and measured in inches?

Spikes are indeed the type of nails that are larger than 20-penny and are measured in inches. Typically, nails are referenced by their "penny" size, with the "penny" indicating the size of the nail in relation to its length. For instance, a 20-penny nail is 20 times the length of a penny, which is about 3.5 inches long. Spikes, on the other hand, are much larger, often exceeding the length of 20-penny nails and can be used in heavy construction work, such as securing timber structures, railroad ties, or in marine applications.

The other types of nails listed are generally smaller than 20-penny nails. Common nails are typically used for framing and other structural applications but do not exceed the size of 20-penny. Brads and finishing nails are designed for light-duty applications and have finer gauges, making them much smaller overall. Double-headed nails, often used for temporary structures or formwork, do not surpass the length of spikes or the largest common nails either. This contextual knowledge about nail types clarifies why spikes fit the criteria described in the question.