The Color property determines the color of all the particles emit by a Smoke object (both existing and future particles). It behaves similarly to ParticleEmitter.Color, except that it is only one color and not a ColorSequence. A color of white with some Smoke.Opacity makes for a nice fog effect, and a very opaque black color can compliment a Fire object nicely.

The Enabled property, much like ParticleEmitter.Enabled, determines whether smoke particles are emitted. Any particles already emit will continue to render until their lifetime expires. This property is useful for keeping pre-made smoke effects off until they are needed later. Since smoke particles are destroyed when the Smoke object's Instance.Parent is set to nil, this property is useful in allowing existing particles the opportunity to expire before destroying the Fire object altogether. See the function below.

local Debris = game:GetService("Debris")
local part = script.Parent
function stopSmoke(smoke)
	smoke.Enabled = false -- No more new particles
	Debris:AddItem(smoke, 10) -- Remove the object after a delay (after existing particles have expired)
end
stopSmoke(part.Smoke)

Opacity determines the opaqueness of the smoke particles. It must be in the range [0, 1]. This property works inversely in comparison to a part's BasePart.Transparency or ParticleEmitter's ParticleEmitter.Transparency: a value of 0 is completely invisible, 1 is completely visible.

The texture that Roblox uses for Smoke particles is partially transparent, so setting this property to 1 still yields transparency in rendered smoke.

RiseVelocity behaves similarly to ParticleEmitter.Speed and Fire.Heat: it determines how fast the smoke particles move during their lifetime. It must be in the range [-25, 25]. Negative values will cause particles to emit in the bottom (-Y) direction of the parent BasePart.

When using a Smoke effect to create fog, set this property to 0. For large smoke effects, make the rise subtle (2 to 8). For chimneys and smokestacks, higher values are appropriate.

The Size property of Smoke determines the size of the newly emit smoke particles. Unlike Smoke.Color, this property will not change the size of existing particles. It must be in the range [0.1, 100]. Unlike ParticleEmitter.Size, this property is only a number (not a NumberSequence). Also note also that the size of the particles is not 1-to-1 with studs; in fact, the size of the smoke particle is more than twice as large. At the largest size, smoke particles can render larger than 200 studs wide!

A value between 0-1 than controls the speed of the particle effect. At 1 it runs at normal speed, at 0.5 it runs at half speed, and at 0 it freezes time.