It likely hasn't seen much use, but I'd ask how many discharges it has done (if the seller even knows.) Has it been stored with batteries in place? Have any of the batteries leaked, causing any corrosion?
The SB-600 isn't bad, but I wish I had bought the SB-900 instead, even though it is double the price. Hey, buy mine instead! $200 shipped Priority Mail, plus a Sto-Fen Omni Bounce and all original packaging. About 200 discharges (not many in other words....)
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Scott
2024 G01 X3 M40i, Brooklyn Grey Metallic /// 2015 F15 X5 35i, Space Gray Metallic, 99K miles /// 2013 F30 320xi, Mojave Metallic, 112k miles
2019 Ford F450 STX, Oxford White
2013 Ducati Multistrada Touring S, Red