Alien I has two conventional springs.
Alien II has a four internal cam springs.

↑ Set 206-208: CCH Aliens

• Made in USA [ca. 1996].
• 3/8–3/4

↑ 206: CCH Alien I

• Made in USA [1995].
• 3/8: 11 mm.

↑ 207: CCH Alien II

• Made in USA [1995].
• 1/2: 16 mm.

↑ 208: CCH Alien II

• Made in USA [1995].
• 3/4: 21 mm.

↑ 376: CCH Alien II

• Made in USA [ca. 1996].
• 2: 49 mm.

↑ 377: CCH Alien II

• Made in USA [ca. 1996].
• 2 1/2: 59 mm.