CC1101
The most common radio device used for evohome (RAMSES) listening devices is a cc1101 module. This is also used in a number of Honeywell devices.
There are a number of modules available that include the components required by a cc1101 to provide an MCU with the 868MHz radio interface required.
The most commonly used module is green 
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This module appears to be produced by a number of different (anonymous) manufacturers.
There is a wide variation in the physical appearance.
The holes on the left side are all pitched at 2mm but the finish varies.
- they can be simple complete holes as shown above.
- they can be crenelated like the holes on the right
- they can be cut so they are just open holes.
The holes on the right vary in the same way but can have both 2mm and 2.54mm picth
The quality of the 26MHz crystal used is very unpredictable. There have been a number instances where the accuracy is such that the cc1101 cannot easily lock on to the 868.3Mhz carrier frequency used by evohome equipment.
An alternative module is red 
These appear all to be produced by a single manufacturer EByte .
These modules appear much more consistent in both overall appearance and the quality of the components used compared to the green module
Red PCBs are typically used for prototypes
The first production variant of the Red Module from EByte
Used in the Original SSM-D2, it measures 14x20 mm
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A smaller version of the E07-900M10S from EByte
Used in the SSM-D2 Revision B, it measures 10x10 mm.
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