Three Types of Dallas keys – Magnetic and non-magnetic iButtons
A magnetic dallas key is also called a magnetic iButton. A magnetic dallas key (magnetic key in short) consists of a iButton (most common DS1990A+F5/DS1990R#F5), an outer iron ring(iron/Ferrous or stainless steel) and a plastic holders. This type of keys can only work with a magnetic reader with magnets inside.
Browse magnetic dallas keys with iron rings
Non-magnetic Dallas key consists of an iButton (most common DS1990A+F5/DS1990R#F5) and plastic holder (without the outer rim). Non-magnetic keys should work with non-magnetic reader, with OR without LED should be OK.
Browse non-magnetic dallas keys
Beside these magnetic and non-magnetic keys, actually there is another type of keys that really have magnetism (with magnetic outer rim). This type of keys consist of an iButton, a plastic holder and a magnetic outer rim. These keys can work with non-magnetic reader as long as the reader has an iron ring for the ground. This truly magnetic keys should work with non-magnetic reader but with an iron outer rim.
Comparison of three types of Dallas keys
| type | Non-magnetic dallas key | Magnetic dallas key with iron outer ring | Magnetic dallas key with magnetic outer ring |
| Picture |  |
 |
 |
| Constitute | iButton
+Plastic holder |
iButton
+ iron ring + Plastic holder |
iButton
+ magnetic ring + Plastic holder |
| Reader | Non-magnetic reader, body can be any metal | Magnetic reader with magnets inside, body can be any metal |
Non-magnetic reader .body should be Iron or stainless steel with magnetic property |
*Note: iButton and 1-Wire are registered trademarks of Maxim.