Does not work.
(I tried with R15 and R6)

local FolderWithAccessories = game.ServerStorage:WaitForChild("fasthelmet")

game.Players.PlayerAdded:Connect(function(player)
	player.CharacterAdded:Connect(function(char)
		player.CharacterAppearanceLoaded:Wait()
		for _, accessory in pairs(FolderWithAccessories:GetChildren()) do
			if accessory:IsA("Accessory") then
				char:WaitForChild("Humanoid"):AddAccessory(accessory)
			end
		end
	end)
end)