These adapters are special, and only the freaks of you will notice that. The PMPM+20/23mm adapter has 4 bolts, but looks tiny just like one with 2 bolts. The difference is: the normal 2 bolt adapter needs to have spherical heads and washers, which are able to compensate the small angle difference between fork and caliper. With the Extension brake adapter you have a solid 4 bolt mounting of your caliper, with a clean looking appearance.

And the second point is, you can mount it as a +20/40 or +23/43mm. Without extra parts.

Features
+20/23mm version: Suitable for +20mm and +23mm
+40/43mm version: Suitable for +40mm and +43mm
Includes: All necessary bolts and washers
Material: Titanium upper bolts, sleeve and washers

Mfr Claimed Weight
26g (+20/23mm), 32g (+40/43mm)