You will get a reply from Steve Neul saying that they are "junk" but if it works for you then great. The issue is the centerline mark is or may be off center. Maybe we got lucky and got 2 good ones, but even if so, you can always scribe a new mark in the center.
I thought it might make a self centering mortise jig and I'm still trying to sort that out. I looked at a General Tools mortise jig and was shocked to find out it was $99.99 at the Performance Tool store. That just seemed like too much.
Doweling is always a bit tricky. Have you used the marking points that fit in one hole and leave a mark on the joining piece?
Dowel Accessory Kit
Doweling Accessory Kit Stock up on supplies for your next doweling or joinery project!
• 3 Brad Point Drill Bits: 1/4", 5/16", & 3/8"
• 3 Drill Stops: 1/4", 5/16" 3/8" & Hex Wrench
• 3 Steel Drill Bushings: 1/4", 5/16", 3/8"
• 6 Dowel Center Points: 2 each of 1/4", 5/16", 3/8"