GrowthFactor is an Integer property that indicates the threshold to use when reallocating internal storage for the buffer. 

GrowthFactor is used in Remove to determine when unused byte values at the head of the buffer have exceeded the desired threshold, and forces unused space to compacted. 

GrowthFactor is used in Write to indicate the number of unused bytes to allow at the tail of the buffer following removal of unused bytes at the head of the buffer. 

Use Capacity to indicate the maximum number of bytes allowed for the internal storage of the buffer.

TIdBuffer.Capacity 

TIdBuffer.Size 

TIdBuffer.Remove 

TIdBuffer.Write