The Delayer is a machine added by Integrated Dynamics. It is used to make an active list of whatever variable is placed into it.
The interface shows 2 values under the 2 slots. The top slot is for the variable card to read from, this card must stay in the slot. The bottom is for a secondary card for the active list of the top card to be written to. The tick value determines (in ticks) how often to refresh the list. The bottom value is how many times the Delayer should hold the value, or how long the list will be. For example, selecting 5 will show the value 5 times in the list.
To make it work the player needs a Reader with a Variable Card linked to it that can feed a variable it can use. Place an Inventory Reader on a chest and connect it with cables to a Delayer. Place cables from the Delayer to a Display Panel; it is easier to place the panel on the cable than place cables to a panel. Place a Variable Card in the Inventory Reader's slot for to write content to it. Remove the card and place it in the top slot of the Delayer. Place a new Variable Card in the bottom slot WHILE the first Variable Card is in the top; do not remove the top card.
Place the new Variable Card that just got written to in the display panel, it will show every time the chest's contents changes.
The card in the Display Panel can be used with a Portable Logic Programmer to be used as a list to read from with some other variable card logic.