I'm going to say it is a prototype for the discontinued "670 Apparition" model. It almost became my first ever Benchmade. Some say it was the precursor to the current Benchmade Barrage family of knives sans the axis-lock. There was also a "Limited Edition" of the model named the 670DM-502 NICA that came with a "Hakkapelitta Damasteel" blade and carbon fiber handle scales. Finally, there was an in-between model named the 670-501 that was the same as the 670, except for having S30v blade steel.
Follow the links below for interesting information about both versions at Benchmade's website.
670:
http://www.benchmade.com/products/670
670DM-502 NICA:
http://www.benchmade.com/products/670DM-502
Product Number: 670 Apparition
• Option of spring assist or manual opening
• Attractive bolstered handle design
• Locking-liner mechanism
• Removable pocket clip
Designer: Warren Osborne
Mechanism: Modified Liner Lock w/Optimiser Spring-Assist
Blade Material: 154CM (S30v for 670-501)
Blade Style: Wharncliff; Thumb-Stud
Blade Length: 3.4 in.
Blade Thickness: 0.125
Blade Options: Plain Edge; ComboEdge; Satin or BK1 Coated
Handle Material: Black Valox 420
Liner Material: 420J SS
Back Spacer: Stainless Steel
Sheath/Clip: Stainless Steel, silver split-arrow clip mounted right of handle, tip down carry.
Weight: 4.50 oz.
Length-Open: 7.82 in.
UPC: 6 10953 12016 0
MSRP: $150.00
