Quick view 18" x 4.5" Aluminum Toroid, Seamless 18" x 9" x 4.5" Aluminum Toroid, Seamless This heavy duty, seamless toroid is the one used in our Plasmasonic 1.3, Reference Design 1.0, and Best DIY 6.0 Tesla coils. It is made of 99% pure (grade 1100-O) aluminum, heavy duty, and welded with no... MSRP: Was: Now: $349.99 Add to Cart