Già nel 2010 la Feather informava un cliente che le lamette nella confezione nera sono identiche a quelle nella confezione gialla, l’unica differenza è che le nere sono confezionate in pacchi da 5 mentre le gialle sono in pacchi da 10:

Dear Mr. ******,

Thank you very much for your e-mail dated December 10, 2010 through our website.

Regarding your inquiry about our double-edge blades in different packaging, please be advised that there are no difference in quality of blades between yellow package and black package.These are completely same products just in different packaging. (Please be advised that the black package contains 5 blades and yellow one contains 10 blades.)

Thank you very much again for your interest in our products, and please feel free to let us know if you have any further questions.

Best regards,
Tsuyoshi Ishiyama
FEATHER SAFETY RAZOR CO.,LTD.
OVERSEAS TRADE DIVISION

FEATHER BLDG.5TH FL.
5-2, DOJIMA 1-CHOME
KITA-KU, OSAKA 530-0003, JAPAN

Armando Ilič Misasi, 29 gennaio 2018