> De Tails are here:  http://www.3dlens.com/wideanglefresnellens.htm

you can also find them at local RV suppliers ... the lenses come in
different sizes and are made by 3M ...

here's a write-up i did for the list a loooooong time ago ...

rear window: 3M has a thing called Vangard. it is a fresnel
lens that allows you (in the driver's seat) to see things right at the
bumper. well, almost. you really can see things close up much better.
they come in three sizes:
part number: 07950  Vangard          8"x10"
             07951  Super Vangard   11"x14"
             07952  Vangard 2        6"x8"
costs about $10 for the middle size ... mine is the 6"x8" one ...
and i find i really can't do without it now.

http://www3.3m.com/catalog/us/en001/home_leisure/-/node_Q8NTXBDZNFbe/root_GS2MT8MCQBgv/vroot_BWFLZ648DFge/gvel_V81136SWNHgl/theme_us_chimpartnersupport_3_0/command_AbcPageHandler/output_html

http://multimedia.3m.com/mws/mediawebserver?66666UuZjcFSLXTtMxf2l8&_EV76EbHSHVs6EVs6E666666--

http://www.mettamsafety.com/default.aspx?page=item%20detail&itemcode=3M+07950

http://www.shophsg.com/vawianvile.html

so check around ... they're still out there. just more expensive. :(

good luck!
unca joel