Santana's Winzip is a re-branded and slightly modified IRD Dual Banger.

IRD has a cut-sheet on their Website: http://www.interlocracing.com/mech_instr2.pdf

Santana also has some info on theirs: http://santanatandem.com/Library/WinzipDiscInst.pdf

FWIW, as you might expect, there are a number of Santana tandem owners who frequent the tandem list that have the WinZip brake. Bloomingcyclist is one of those who has posted some reviews of his Winzip with both the OEM pads and some better performing aftermarket pads. A search on his logon name with the search term 'Winzip" would likely yield some useful information.