This is an antique Petzl "Zedel" Chest ascender. It's clear that the Basic design was inspired by this and the Basic merely switched from ribs to spikes. Branding saying "Zedel" - who owned the patent - now Petzl I haven't tested this out in an ascent situation so you can choose whether you want to do that. No returns. Already priced as low as it can be #133
eBay