Originally purchased these for my Martin GPCPA3 which I've sold, ended up not using them as I was happy with the action and had a Huss & Dalton at the time so didn't really need the GPCPA3 to have the bone nut and saddle unplugged tone.

You would buy this if either:

A. You f'd up your Martin D18 or D-28's action by sanding the saddle too low and don't want to dampen the tone with a shim.

B. You own a sub-standard series Martin (anything below a D-18) or one of the PA series and want to upgrade from Corian/Tusq.

C. You've had a standard series Martin for say five years and the string groves require the nut and saddle to be changed.

D. You want to experiment and try out your skills as a luthier.

Brand new prices from Bob's website are here:

http://guitarsaddles.com/pricing.asp

Nut ($25) Martin standard drop in saddle ($20) Shipping ($23)

Note that these are USD, so in total you'd be paying:

$68 USD - i.e. $80.14 NZD

Since I've sold both my Martins, I have no need for these products anymore.

Just do a Google search for Bob Colosi and people's reviews of his products on guitar forums etc. You won't find a single negative one.