In the three decades since spring-loaded camming devices were invented, they’ve radically transformed the notion of what climbs can be led safely. Here’s a little lore about modern climbing’s most revolutionary piece of protection.

1 The essential brilliance of spring-loaded camming devices (SLCDs) is their lobes’ shape, which is described mathematically as a logarithmic spiral. The same curving lines are found naturally in seashells, pine cones, flower heads, and even in the basic form of our own galaxy, the Milky Way. Logarithmic spirals are ideal for camming units because no matter how retracted (or nearly tipped out) the cams are, the lobes contact the rock surface at the same angle. Changing the tightness of the lobes’ spiral can change both the cam’s range and its camming angle. But it’s a tradeoff: Increasing the cam’s angle increases the range, but it also decreases the force exerted by the cam’s lobes on the sides of a crack when a climber weights the device. That means cam manufacturers have to strike a balance between the cam’s range and its holding power.

2 These days, climbers tend to use the word “cam” to refer to SLCDs, but, technically, a cam is any tool that can transform linear motion (like a fall) into rotary motion (the rotation of a piece of pro to wedge it more firmly into place). That means hexes placed in a particular orientation, Tri-Cams, and even Big Bros qualify as cams, even though they have no springs.

3 It’s not completely clear who first developed the idea of applying a curved camming surface—modeled on a logarithmic spiral—to climbing protection. Russian climber Vitaly Abalakov invented a piece of gear that looks very similar to today’s Tri-Cams. At about the same time, Greg Lowe was working on a similar piece of climbing equipment in the States. In 1972, Lowe introduced the Cam Nut, a spring-loaded device with a single lobe and a single stem. In Lowe’s 1973 patent, he clearly articulated the idea of creating a curved device to create a constant camming angle. Lowe’s wobbly Cam Nut— which sold for $3.95—and its successor, the twin-stemmed, two-lobed Split Cam, were never commercial successes.

4 The inventor of the modern SLCD was Ray Jardine, who was inspired by the constant-camming-angle concept in Lowe’s Cam Nut. Jardine, an aerospace engineer by training, had already been tinkering with new climbing gear for a couple of years when he first got a look at the Cam Nut in 1973. By spring of the following year, Jardine’s prototypes—which would later become Friends—were ready for a trip to Yosemite Valley, where Jardine used them to dispatch a slew of diffi cult-to-protect climbs. Jardine, who later became a pioneer of ultra-light backpacking techniques and equipment, used his SLCDs to put up one of the world’s first 5.13s, The Phoenix (5.13a) in Yosemite Valley, in 1977.

5 Early on, Jardine kept his arsenal of new camming devices cloaked in secrecy. Fearing that his game-changing idea would be ripped off, he swore his climbing partners to silence. And the name that his camming devices ultimately would take was born from Jardine’s secrecy. He was known to carry his prototype cams in a blue nylon bag so no one could get a look at them. One day, when Jardine was preparing to go climbing, his partner, Kris Walker, wanted to know if the blue bag of goodies would be coming with them for the day. But since other climbers were around, Walker coyly asked Jardine if he had brought the “friends” with him. The name stuck.

6 In 1977, a trusted friend of Jardine’s, Mark Vallance, started the gear company Wild Country in England to begin commercially manufacturing Friends. The first advertisement for Friends appeared in Mountain magazine in 1978. It called the devices “the revolution in climbing protection: vertical, horizontal, parallel-sided or even flared cracks—Friends work better and faster than any other device.”

7 Not everyone embraced the revolution. When Friends hit the market, some climbers denounced them as unethical, saying they made climbing too easy. Steve Levin, in Climbing No. 51 (1978), wondered whether Friends’ use should lower a climb’s technical grade, and whether it would be poor style to repeat a climb originally protected with chocks while using cams. In an interview for Climbing No. 170 (2008), the 1970s rock legend Henry Barber said he still didn’t use SLCDs. “I have cams, I’ve just never used them. They’re awesome, brilliant devices—fantastic technology. I’ve got nothing against them—I just never needed them.”

8 The first SLCDs with flexible stems were created by Steve Byrne, who also cut the number of lobes on his design from four to three for narrower placements. In 1985, he began commercially producing his Three Cam Units, which had a flexible U-shaped stem, in Flagstaff, Arizona, under the company name Wired Bliss.

9 When Black Diamond’s Camalots first came on the scene in 1987, they added another new dimension to camming units: the double axle. The design, created by Tony Christianson, allowed the Camalot to get greater range without sacrificing holding power.

10 Today, the largest SLCD a climber can buy is made by Valley Giant, which sells two sizes of cams: the VG9 and VG12 (nine- and 12-inch spans). They’re available by special request and cost $175 and $225. The smallest cam on the market is the Wild Country Zero, size one, which will protect a crack as small as 0.22 inches.