Unusual Tool On Ebay

[spooky]

I was having a look at leatherwork tools on EBAY and came across this. I'm just wondering if anyone might be able to tell me what it is, and what it is used for? Thanks.

http://www.ebay.com.au/itm/ANTIQUE-UNUSUAL-SADDLERS-ADJUSTABLE-CUTTING-TOOL-like-a-SMALL-PLOUGH-VGC-/321036678753?pt=UK_Collectable_ToolsHasdware_RL&hash=item4abf46f661

[Jax]

Hi it looks to me to be a martingale groover, it cuts a slit in the leather & can be adjusted for both the width & depth of the cutI use mine mainly to sink my stitches into the leather when making rolled straps so when they are completely finished no stitches can be seen.

[spooky]

Thanks - I'd never seen one before.... but that shouldn't surprise anyone, given how new I am =)