FY - stands for Cobra® Pro Style buckles - a modernized model with a different shape of curves, preventing blocking with one lug, easier access to cooperating elements for cleaning.
50mm - means the width of the webbing slot,
K - stands for KTL Black colors,
V - means adjustable male half (V - versatile),
F - means female half constant (F - fixed).

Extended description in the article...

According to the manufacturer's instructions for the AustriAlpin buckles, there is only one way to properly install the webbing in the adjustable buckle with a self-locking beam.

Thank you EDCreview!

Link to full review of Bayonet belt.

Sklepy współpracujące w Polsce

4Shooter Warszawa Pasaż Ursynowski 3

3CityTactical Sopot ul. Jana z Kolna 35

Besthunters Warszawa Jutrzenki 91

e-Militaria Wrocław Różyckiego 1c/311

Jar-mix Militaria Słupsk Mikołaja Kopernika 2

Khakishop Kraków Rynek Główny 7/12

Military Zone Żywiec Dworcowa 10

Pentagon Katowice Mlynska 17

Predathor Warszawa Ogrodowa 4

Specshop Poznań Małe Grabary 2

Sprzętmilitarny Jarocin / Witaszyce Witaszyczki 66

Suwenir Częstochowa Św. Brata Alberta 3

TM Militaria Warszawa Bluecity, Tamka, Wola, Kraków, Gdynia, Szczecin, Wrocław, Katowice         

International Cooperators

Bayixiaoqu, Duyun city, China

Dodo_ss shop, Jiangxiaojing, China

Huiqian, Beitangqu Wuxi City, China

Mgear, Chengdu Sichuan, China

DiS. Bogdan Jakubek Vendryne 1179, 73994 Vendryne, Czech Republic

BUSHCRAFTshop.cz Jesenicka 22, 78701 Sumperk, Czech Republic

Baltic Fox OÜ Raua 1/ Pronksi 6 Tallinn, Estonia

TACGEAR OÜ Kuru 8 50105 Tartu Estonia

Shanghai YanHe Network Co., Ltd., Hong Kong

Dark Tactical Ltd, Szeremi Sor 6, 1117 Budapest, Hungary

Landforce Via Lucrino 27ª, 00199 Roma, Italy

Utstyrskontroll AS Vindalsasen 43, 3728 Skien, Norway