In an example, monitoring circuitry includes a first and second coupling, at least one of which is to capacitively couple the monitoring circuitry to a monitored circuit on a product packaging. The monitored circuit has a resistance which is indicative of a status of a product stored in the product packaging, and the monitored circuit is to be connected in series between the first coupling and the second coupling. The monitoring apparatus may determine the resistance of the monitored circuit via the first and second couplings.
