Pats key has the keyhole in its head off center so the little glass module will fit in the key head, and it's about a 1/4" thick, and you can see a little plastic square plug on the top side of it to hold in the responder. See that coil of copper wire, thats its antenna to cummunicate with the ECM, and the other two little squares are probably the micro chips in it.
I took one of those fat boys apart in the lockshop to see exactly what was there. A glass tube that actually holds a miniature crystal radio, and it communicates with your ecm to start your ride once its programmed into it. One and a 1/4 inches wide, by about 2/8's or so.
~Draw me not without reason, Sheath me not without honor~ 17th century swordmaker Gallegos
~1994 Ford Ranger 2.3L 4-Banger 217, 000+miles~