A double-ended LED tube is a tube that has the live and neutral pins on the opposite side of each tube. Fluorescent tubes are typically double-ended as well, making retrofit applications easier to complete with double-ended LED tubes.
A double-ended tube can use either shunted or non-shunted tombstones. When upgrading to LED tubes using an LED Retrofit Kit, you can the existing tombstones if they are in good condition, helping to reduce the average retrofit installation time. Check any tombstones to be reused for damage. It is not uncommon for old tombstones to be broken either from long exposure to heat or from replacing the tubes. If damage is found it is best to replace them.