The secondary coil terminals are 4 1/2 inches apart and I have had a spark jumping between these terminals without the discharging pins fitted! I imagine a longer spark would be possible with a remote spark gap, but I didn't want to push it, I would normally settle for a 3 inch spark with a coil of this size which is more than enough for powering up the usual Geissler and X ray tubes.The whole assembly is mounted on a polished lacquered wooden plinth which houses the capacitor. The coil is shown energising a large and small Geissler tube and a Neon spectral tube, these are not included in the sale. I have a large collection of induction coils so when I say this one is fierce and viscous, I do know what I'm talking about, with respect! This instrument takes me back to my college days, (over 40 years ago), when we did real science... The coil appeals to all the senses, not only sight and sound, you can smell and taste the ozone produced and if you're not careful feel the 100,000 volts and probably view an X ray image of yourself on the wall behind you! NB DO NOT USE THIS COIL IF YOU HAVE A PACE-MAKER FITTED, your last heart beat could be a big one!! Overall width of base: 18 inches. Coil dimensions: 10 inches long x 4 inches in diameter. Please ask for a more accurate quote to your specific country. Please feel free to have a look at my other items. The item "INDUCTION COIL, HUGE, FIERCE, VINTAGE PHYSICS STUNNING CONDITION & WORKING" is in sale since Thursday, November 14, 2019. This item is in the category "Antiques\Science/Medicine\Scientific Instruments". The seller is "chemistry63hg" and is located in Newcastle, Staffordshire. This item can be shipped worldwide.