NOTE: Bonanza does not require an account. Just add the item to your cart and proceed to payment. ***DO NOT use this tester on anything except Mercedes glow plugs from this era and other high voltage plugs. Other glow plugs won't survive the test. This is for an extremely rare BERU glow plug tester made in West Germany specifically for the OM61# engines. This was the era of German companies getting major boosts for all things W123. This tester enables you to test your glow plugs quickly and accurately without having to remove them from the engine. This is from the 80's when BERU was a major supplier for Mercedes diesels. For whatever reason BERU never marketed specialty tools like this outside of Europe. The markings on this are all German so a translation is included. After you do it once you'll know the tool. One of the standard methods to test your glow plugs is to remove each one of them. It is tedious and the down time always runs long just for poor information after running each plug directly off of the battery(flawed test at full 12V) and watching them glow. Which ones are good? If one is glowing at 1000'F and the other 4 are brighter at 1300'F they're all bad because good plugs glow at 1650'F. Next you could check resistance. Another way is to replace all of the glow plugs at one time(max labor and parts) but if the problem is just one plug then replacing all of them is excessive. The easiest by far is remove the wire from a glow plug, connect this tester and press the button. This tester is a major time saver plus it's accurate. The only time you should pull a glow plug is if you already know it's bad. This tester also bypasses the glow plug relay and runs the entire test through the device so you're not turning the key every time. This tool will also tell you if a glow plug is bad due to a direct short by blowing its onboard fuse. This takes a standard Mercedes euro type 16A protection fuse inside the unit just like a multimeter. If all of the plugs test good then the glow plug relay or the wiring is suspect. Markings on front: Gut = Good Defekt = Defective testbereift = Ready for test Test lauft = Test is running Schnelltester = Quicktester fur 11 volt = For 11 volt stabgluhkerzen pin glow plugs As per the tool OM61# glow plugs are run at 11 volts which in the world of glow plugs classifies them as "high voltage." Most glow plugs are run at 6 volts or less which cannot handle this MB specific tester. Free shipping in the U.S. If there's a problem let me know and I'll work with you. My work keeps me away often so to be safe, handling time to get this shipped out is 1 week. SHIPPING ADDRESS: I can only send your item to the registered shipping address at time of payment.