D meaning on Chinese AK47 and SKS rear sight

What does the D mean on Chinese AK and SKS? This video answers that long lost question.

*Product sponsors & coupon codes:

Kore Essentials belts https://www.koreessentials.com/
for 10% off use code - CAVSCOUT10

Otis Technology (firearm care store, cleaning kits)
https://www.otistec.com
for 15% off use code CAVSCOUT15

Shooters Choice (firearm care store,cleaning kits)
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for 15% off use code CAVSCOUT15

Cav Hooah!
(online Cavalry Trooper, Scouts, US Army store)
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for 5% off entire order use code - CAV19D
(not available on Stetson brand Cav hats, all other Cav hats brands the code can be used for)

Olight weapon lights and flashlights
http://www.olightstore.com/s/758KS1
for 10% off use code - CAVSCOUT10
(not valid on sale items or X9R)

FAKEBULLETS.COM (inert training rounds/dummy rounds/snap caps and so much more)
https://www.fakebullets.com
for 5% off use code - CAVTROOPER

Patch Ops (Tshirt, Morale patches, & stickers)
https://patchops.com
for 20% off first order use code - CAVSCOUT20

Rad Labs 3D display stands
https://www.radlabs3d.com
RL3D makes the AR-15 and AK-47 stands I use. Just tell Saul, “Cav sent me” he will get you taken care of. Sadly no coupon code

Patreon:
https://www.patreon.com/CavTrooper19D