I have never heard of Sunmeadow.

The concept is British perhaps thirty or more years old and is now manufactured here in the UK by a company who trades as Hotcan. (Do a search for Hotcan) I have used them professionally for years for feeding firefighters and did have a batch that did not heat, I returned them and the replacements were fine, just a bad batch. The owners of Hotcan have changed a few times over the years, I expect because even though it is a good idea few people buy them often enough, once they were marketed as ideal for the city type who did not have time for breakfast!!

When you pierce the top you burst a bag of water which drains into quicklime in the space between the cans. This causes an exothermic reaction which heats the meal, normally to boiling, at least far too hot to touch the bare can.

The contents in the UK are very good flavour and quality with a wide choice, I have never had one I did not enjoy if a little short in the amount of what someone active in the field wants to eat.

They are great for hot snacks for emergency workers, quick, simple and you can get a few more hours work out of them before having to stop for a real break.

Probably OK for emergency stores but are expensive for the amount of food in them, better a few cans and an external cooker.

For hiking pretty useless, expensive, heavy and generate a lot of waste to get rid of.