Hi,
     I have the following questions:
1.  I have found this wireless ear receiver
http://www.ottoeng.com/comm/wirelessaccessorieshome.htm. I want from
you to find a smaller and more discreet ear receiver and some special
techniques in order to make the device stealthier.
2.  I have found this pen camera
http://www.boysstuff.co.uk/product.asp?id=1655 . At features you can
see that the maximum transmission range, in line of sight, is 100 m. I
want from you to find a stealthy way to expand the maximum range so it
can transmit at distance 150 m through 2-3 thick walls or a similar
pen camera which follows the previous criteria.

Dear nikolaoupan, 

Regarding the pen - it seems that 100m is the biggest range in pens
(other types of equipment, such as bags, teddy bears, jackets and
pagers, have better transmission range).

Regarding the ear-receiver, The PHONAK microEar VHF is supposed to be
the smallest: http://www.lentinicommunications.com/shop/items/item1516.htm

I hope this helped you.