What type of measuring device features an attached dial gauge or digital readout for easier readability?

The instrument featuring an attached dial gauge or digital readout to enhance readability is the vernier caliper. This tool is specifically designed to provide precise measurements of dimensions such as internal and external diameters, as well as depths. The additional reading mechanism, either a dial or digital display, allows the user to obtain measurements at a glance, which significantly improves accuracy and reduces the possibility of reading errors that could arise from traditional scales.

In contrast, other measuring devices like calipers and micrometers, while they can provide accurate measurements, do not inherently include a built-in dial gauge or digital display for easier readability. Calipers may show measurements on a standard linear scale, requiring manual reading and interpretation. Micrometers, on the other hand, provide precise measurements but typically require a more careful reading due to their mechanical scale. Measuring tapes are generally straightforward but lack the precision and detailed readings provided by a vernier caliper.