The EFHW utilizes a 49:1 unun to match the impedance and this antenna works well covering all of the HF bands with the aid of an antenna tuner.
This antenna will work on some bands and harmonics without a tuner however the SWR tends to be high on some harmonics and therefore a tuner is recommended.
The antenna is 21m long and will cover 10m to 40m bands and utilizes the braiding of the coax as a counterpoise and therefore it is essential to have a choke installed on the coax at the radio.
Popular applications are POTA and SOTA activations or a base station with limited space.