BX-166's armor has been made with duranium and plasteel, way more durable and a bit more expensive than the cheap materials the B1 units, so it hasn't been made to be mass produced, since the BX droids weren't as numerous as B1 units.
To illustrate the armor that belongs to BX-166, my droid character
Type and Coverage
Coverage: (Coverage regions for Light armor is 1-3 regions, Medium is 4-5, Heavy is 6-7)
Head: Plasteel "helmet" head
Torso: Duranium and plasteel plated armor
Back: Duranium and plasteel plated armor
Lower Arms: Plasteel plating
Lower Legs: Plasteel plating
Function 1: Jump Boots
This rare and expensive technology is able to propel a person up to 10 meters beyond what a normal person would normally be able to jump, especially when armored. It is not capable of sustained flight, and requires a brief engine cool-down before it can be used again (1 post cool-down)
Function 2: Dart Launcher
Can launch a dart accurately up to 15m. This dart is filled with a fast-acting, short-lived sedative that can render near-humans unconscious, or a sedative tailored to one specific alien physiology. The dart is incapable of penetrating even the lightest armor, or even thick leathers. The dart has the same practical effect as a medium stun bolt.
Function 3: Grapple Line
Grapple lines are capable of supporting the weight of 1-2 people and can launch up to ranges typically up to 15 meters away. Once no longer in use, they are detached from the launcher and left behind. While hand-held grapple guns are capable of auto-winching, armor or wrist mounted devices lack this ability. Grapple lines must be manually activated and controlled by a button or switch.