Which of the following is essential equipment for umpires to carry out their duties?

The essential equipment for umpires in bowls, particularly a tape measure of at least 25 metres long, is crucial for their responsibilities. Umpires are frequently required to determine the distance between the nearest bowls and the jack, especially in close calls where the outcome can significantly affect game results. A tape measure of this length is standard because it provides the necessary range to measure distances accurately on the bowling green, which can be quite large.

While other equipment like digital scoreboards or electronic measuring devices may enhance the officiating experience, they are not strictly necessary for an umpire to perform their fundamental duties. The portable first aid kit, although important for safety and emergencies, does not directly relate to the measuring and judgment aspects of umpiring during a match. Thus, the tape measure stands out as an indispensable tool in ensuring fair play and accurate scoring in the game of bowls.