The following ascenders are all variations of the same basic design, made by the same company under three different names:

Image Ascender Shell Finish Top Hole(s)Bottom Hole(s) Cam Stop
Anthron AB-20, Version A Anthron AB-20, Version A Anodized Two carabiner-size Two carabiner-size
(one with webbing slot)
None
Anthron AB-20, Version B Anthron AB-20, Version B Anodized One carabiner-size, one small Two carabiner-size
(one with webbing slot)
Stamped
Lucky AB-20 Lucky AB-20 Anodized Two carabiner-size Two carabiner-size
(one with webbing slot)
None
RollGliss 250 Rollgliss R250 Painted One small One carabiner-size Stamped
VauDe AB-20 VauDe AB-20 Anodized Two carabiner-size Two carabiner-size
(one with webbing slot)
None

The Anthron AB-20, Version B differs from the others by having a stamped cam stop and a smaller secondary top hole. The Rollgliss R250 uses the same shell and cam as the Anthron AB-20, Version B (including the cam stop), but has fewer attachment holes, making it slightly heavier and less versatile.

These are well-made ascenders and perform much like the Petzl Basic. All sharp edges have been removed. The cam teeth are very well done. The attachment points are simply holes in the shell, and although rounded they should have been beveled more; even so, I would consider their small radius too sharp for directly attaching rope slings. They are acceptably rounded for webbing, and the unique slot on those that have it makes it easy to sew webbing (up to 35 mm.) in place. Considering the proximity of the attachment points to the main rope, I would recommend using a small maillon for most rope attachments in order to reduce the risk of sling abrasion.

The upper rope attachment hole through the rope channel is located very close to the main rope . A carabiner through the upper attachment hole will probably drag on the main line. Note that such a carabiner will prevent putting the ascender on or off rope, so one's climbing system must be designed accordingly.

The safety is awkward to use with one hand (like the Petzl Basic). The cam is very well made. The notches don't seem to provide much help in muddy conditions - but nobody else's similar ascender works well either. I'm not sure what purpose the bar serves - several people have sent me emails telling me that the bar keeps the cam from closing and touching the shell. I agree, it does, but so what? Putting the ascender on rope does the same thing. Initially I wondered if the bar would interfere with using the ascender. It does not appear that it will, at least on 9 mm and larger ropes.