Kevin Jones wrote:
> The base module that the spark fun device uses is only $35.00
>
> http://www.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMtqO%252bWUGLBzeMW4TCGBne5E
>
> and much lower in quantity. However, its a 3.3v device and requires
> SMD soldering skills. The extra dollars to spark fun are for a 5v
> interface and having already soldered to a board that is easier for
> hobbiests to work with.

Kevin, I have a feeling that you don't understand what STM4100 is. It is a 
module that has all the features of the SparkFun DIP (on-board 5V regulator, 
development-friendly connector), and in addition also has circuitry that 
allows it to automatically go "bus-off" when a serial or USB cable is 
plugged into the same circuit. It has a much smaller vertical profile, and 
requires only a 2x6 2mm header on one side (so it does not intrude as much 
on the host PCB).

You get all this, for only $4.95 more than you would pay for the bare RN41 
($39.95 vs $35), and $20 less than you would pay for the SparkFun module.


> However, looking at the bottom picture of the device, I'm not sure
> its all that much lower in profile. There are jumpers and connector
> on the bottom of the board. The spark fun module is smooth on the
> bottom, no components.

Here's a picture I just took, of two old lab samples (I apologize for the 
quality):

http://maksimov.org/piclist/sparkfun_vs_stm4100.jpg

Notice that the connector on STM4100 is female, and the holes go _through_ 
the PCB.

Sparkfun's module was designed to plug into a breadboard, where space is not 
an issue. STM4100 was designed to be used in a production device with a very 
low vertical clearance:

http://www.scantool.net/elmscan-5-bluetooth.html

I hope it all makes better sense now.

Vitaliy 

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