We found the Greentek Gelfree S3 cap first presented by Krisztián Hofstädter in the www.openbci.com forum: Krisztián Hofstädter has only an EEG signal on 2 channels of his cap. The other channels have no signal and are covered by his head. Peter Gamma from www.petergamma.org has discussed this cap with Krisztián Hofstädter in the www.openbci.com …