I stumbled over this Sandberg in local ads and I can't find any info anywhere on a Thinline like this! First of all, it's fretted, whereas most Thinlines I've seen are fretless. Second, it's 6 stringed - I've only ever seen 4s and 5s! Third, it has a J pickup, where most other Thinlines I've seen have one of those weird Delano X-tender pups. It's passive - only a volume and a tone - others I've seen have active 3 band EQ. So what's the deal? Is it "just" a custom shop or have these been in production in the past? How much would you value it in a second hand deal, considering the condition is good?