They were cheap enough that I shouldn't complain, but they weren't exotic devices; They are a ring depth gauge with a set screw. The set screws were so junk they snapped off immediately making depth adjustment impossible and very difficult to remove. If the seller is looking for a long-term business, please take my advice - "QUALITY IS STRONG" is the credo of many companies that have been around for a long time. Offer the best and people will keep looking for you - or - offer rubbish and spend all your profits on advertising to lie to your throwaway customers. PAY ATTENTION