They are dark red. They are not hot, and are slightly sweet. They have more heat than paprika, less than cayenne.
They are harvested, then soaked in olive oil, then processed for a week by drying them in the sun during the day, and each night, wrapping them up so that the peppers sweat. They darken further as they dry, becoming a dark purple, and naturally develop an aroma that is almost smoky.
Then, they are ground into flakes for sale as dried, flaked pepper to be used as a table condiment.
On a scale of 1 to 10, the heat is 3 to 4.
Urfa is a city in south-eastern Turkey, near the border with Syria.
In Turkey, red pepper flakes in general are called Isot. The best known is Urfa Isot.
The pepper itself is called “urfa-biber” in Turkish, or “Isot”, or “Isot Biberi.”