Philips Softone 60w 10 hour free trial lamp

I recently found this in a lot on Facebook local and was very happy when they agreed to sell separately. I have only ever seen one of these before in someone else's collection, it seems these free trial lamps were also offered in various colours like the normal Softones. What I don't understand is how it is designed to last 100 times less than a conventional lamp, when testing it it didn't look at all overdriven. Overall, a rare and interesting lamp which I am happy to have found as a Softone lover.