As detailed here: IRISS Overtemperature Indicators for cabling
I have a handful spare IRISS Overtemperature Indicators as the minimum order quantity was bags of 50.
H1(for cable diameter 2.3-4.2mm) 50p
H2(for cable diameter 4.8-7.1mm) 75p
H3(for cable diameter 8-13.6mm) £1
These prices are at cost plus a couple of pence rounded up to sensible numbers.
Items will be sent Royal Mail Large Letter Tracked 48 at a cost £2.70.