The is one of the following group of closely-related chest ascenders:

Image Ascender Shell Cam
Safety
Made
Advanced Base Camp, Version A Advanced Base Camp,
Version A
Anodized Large Loop Feb. 2006
Advanced Base Camp, Version B Advanced Base Camp,
Version B
Anodized Pin Feb. 2007
Advanced Base Camp, Version C Advanced Base Camp,
Version C
Anodized Small Loop Feb. 2007
Climbing Technology Chest Ascender Evo Climbing Technology
Chest Ascender Evo
Anodized Small Loop Feb. 2014
Climbing Technology CChest Ascender + Climbing Technology
Chest Ascender +
Anodized Small Loop Jun. 2017
Climbing Technology Chest Ascender HC Climbing Technology
Chest Ascender HC
Hard Coat Small Loop Jan. 2020
Image Ascender Shell Cam
Safety
Made
Cypher Chest Ascender Evo Cypher Chest Ascender Evo Anodized Small Loop Mar. 2017
Edelrid Windup Edelrid Windup Anodized Small Loop May 2016
Repetto Cirano Repetto Cirano Anodized Small Loop Feb. 2007
Singing Rock, Version A Singing Rock,
Version A
Anodized Pin Mar. 2012
Singing Rock, Version B Singing Rock,
Version B
Anodized Small Loop Feb. 2014
 

Obviously, the same people (Climbing Technology Ltd. of Cisano Bergamasco, Italy) made all of these ascenders. These are all well-made and all function smoothly. All sharp edges have been removed.

The Advanced Base Camp Version A is well-made and a number of Frog climbers have told me that they like how smoothly it functions. My testing supports their experience. The large ring on the safety is easy to grasp.

The Advanced Base Camp Version B and Singing Rock, Version A use a pin on a small safety tab. This reduces bulk, but is not as easy to grip.

The small-loop finger opening used on the remaining ascenders is not as bulky as the one on the Advanced Base Camp Version A, but some people may not like the smaller ring because it is harder to operate. I find that my fingers tend to slip off the safety. The end of the safety that locks the cam open is longer than on Advanced base Camp Versions A and B, making the lock-open more secure but also more difficult to engage or release. The shape interferes so the small-loop ascenders not have quite the smooth opening characteristics that the Advanced base Camp Versions A and B have. It also keeps this ascender from opening as far when sliding the ascender up rope. Overall, I prefer the Advanced Base Camp Version A, but John Harman, who has used these more than I have, has an opposing view. John writes:

"The "new" ABC design is much better than the old. The old design seemed to come off rope almost too easy. I never had it inadvertently come off but it never felt as secure as the Petzl. The new design has a much larger tongue that fits up inside the body and makes it much more difficult to come off rope unintentionally."

Neither of us has seen if come off accidentally, but John makes a good point about the relative security of the designs.

The small pin on the cam safety (near the rope channel) performs an interesting function: pushing down on the ring (or post) causes the safety tab to lever the cam open, but not enough to let the rope free. This provides an alternate way to "thumb" the ascender.

The cam closing stop contacts the cam at the same time that the cam face contacts the inside of the rope groove. In any case, the stop only functions when the ascender is off rope, so I consider it to be superfluous. Its only purpose is to achieve a higher strength in artificial tests prescribed by various standards.

The holes in the cam face are intended to reduce the risk of ascender slippage due to mud-caked cam teeth. The design appears superior to some, but most ropes muddy enough to stop other ascenders will stop the this one as well. If you climb muddy ropes, expect to encounter slipping problems with any eccentric cam ascender.

The Climbing Technology Chest Ascender HC has a hard-coated shell that should resist wear better than a standard anodized shell. I don't climb frog often enough to test whether this is a real advantage in the worst cave mud conditions, but it would be worth considering if you are buying a new chest ascender.

The differences between these ascenders are minor, and any of these would be a good choice. for caving. The Advanced Base Camp Version A is currently my preferred chest ascender for the rare times that I climb frog. I like the larger ring on the cam safety, but my decision is also influenced by having a spare that I can dedicate to caving use. If I were a frogger who did not have a chest ascender and needed to buy one, I would consider sacrificing the larger ring on the Advanced Base Camp Version A and choose the Climbing Technology Chest Ascender HC for the hard-coated shell.