new to the site and trying to catch up with all the discussions.
I use an app called giant timer running two old ipads. This enables me to sync the clocks up and makes it much easier to read times than the analog versions installed in most pools. It also makes it easier for the swimmers to keep track of their total repetitions as we start the clock at the beginning of the set so they know how long they have been swimming for and can back count if they lose count.
For the specific intervals there is a bunch of interval training apps I’ve looked at that work ok but personally I prefer my giant clock!