Larry Penberthy tested the strength of wood ice axe shafts and concluded that wood shafts were too weak for safety. MSR's Eagle and Thunderbird were among the first metal-shaft ice axes to address the issue.

Many traditional climbers resisted the transition away from wood shafts. Yvonne Chouinard reportedly even went so far as to call the Thunderbird a "day-glo metal monster more suitable for assassinations than ice climbing."

Nevertheless, the advantages of metal (and later fiberglass and other composite) ice axe shafts over weak wooden shafts untimately drove the latter from the serious climbing market.

↑ 192: MSR Eagle

• Made in USA [1970s].
• 825x270 mm.
• Weight: 790 g.
• Aluminum Shaft.
• Shaft: 34x26 mm.
• Fixed Head with carabiner hole.
• Straight adze with a scalloped edge and a slight arch.
• Adze: 70(l)x70(w)x1(arch) mm.
• Curved alpine pick with a neutral-clearance chisel tip and with 13 ventral teeth.
• Pick: 135(l)x18(h)x7(t) mm.
• Round spike with square base.
• Spike: 65(l)x13(w)x13(t) mm.
• Glide ring missing.
• Similar to the Thunderbird but with a more tradional pick, the Eagle is designed for both ice and general climbing.
• The pick is hollow-ground for easy penetration. The pick's chisel tip is only 4 mm. tall - nearly a point.

↑ 106: MSR Thunderbird

• Made in USA [ca. 1970].
• 750x275 mm.
• Weight: 910 g.
• Aluminum Shaft.
• Shaft: 33x27 mm.
• Fixed Head with carabiner hole.
• Straight adze with a scalloped edge and a moderate arch.
• Adze: 75(l)x70(w)x3(arch) mm.
• Straight swallowtail pick with a positive-clearance chisel tip.
• Pick: 135(l)x18-30(h)x7(t) mm.
• Round spike with square base.
• Spike: 71(l)x13(w)x13(t) mm.
• Glide ring with adjustable web strap.
• The Thunderbird pick was designed with a focus on self arrest. It also performs well cutting steps. Current mountaineering doctrine focuses more on self belay and modern crampons have reduced the need to cut steps.

↑ 124: MSR Thunderbird

• Made in USA [1970s].
• 750x275 mm.
• Weight: 910 g.
• Aluminum Shaft.
• Shaft: 33x27 mm.
• Fixed Head with carabiner hole.
• Straight adze with a scalloped edge and a moderate arch.
• Adze: 75(l)x70(w)x3(arch) mm.
• Straight swallowtail pick with a positive-clearance chisel tip.
• Pick: 135(l)x18-30(h)x7(t) mm.
• Round spike with square base.
• Spike: 71(l)x13(w)x13(t) mm.
• Glide ring with adjustable web strap.
• The rib supporting the adze is smaller than the one on my Thunderbird #106.
• This version has a small hole near the end of the pick. I am not certain which version came first. I don't know what the hole accomplishes placed so far from the shaft. Perhaps it aided manufacturering.

↑ 207: MSR Sumner

• Made in USA [1970s].
• 640x255 mm.
• Weight: 745 g.
• Aluminum Shaft.
• Shaft: 33x27 mm. (Grip: 35x29 mm.)
• Fixed Head with carabiner hole.
• Straight adze with a curved edge and a slight arch.
• Adze: 60(l)x69(w)x2(arch) mm.
• Curved swallowtail pick with a positive-clearance chisel tip and with 12 ventral teeth.
• Pick: 125(l)x11(h)x7(t) mm.
• Triangular spike.
• Spike: 50(l)x20w)x7(t) mm.
• The hook angle is 53° for superior holding compared to 68° for the Thunderbird.
• The pick is thinner and the cleaving angle narrower than that on the Thinderbird, resulting in easier penetration and ledd fracturing in hard ice.
• A previous owner added a nice textured tape to the grip. This provides an excellent grip and some well-appreciated insulation as well.
• Bill Summer had MSR make this model specifically for technical ice climbers.