I tested Bolse 4 port 4 Amps 20 Watt Wall Charger with Nexus 7 Tablet  (JellyBean 4.2.2), Samsung Galaxy 7.7 Tablet (ICS 4.0.4), and Samsung  Galaxy Nexus cell phone (JellyBean 4.2.2), and SanDisk Sansa Clip+  player.
I own several wall chargers and power bricks and run the  same set on tests on each of them, so they can be compared to each other  using "apples to apples" comparison.  This set of tests allows me to  provide unbiased results as the numbers speak for the performance of  each unit.
To test  Bolse 4 port I ran a test for each of my 3  devices on each of 4 ports for a total of 12 tests. I repeated the tests  on both the white and the black version of the wall plug as I received  one of each from the manufacture for an unbiased review. I also charged  the Nexus phone and the Nexus tablet at the same time.  The results of  these 25 tests are included in the tables below.
➨ Key finding:
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I  am include results from testing both the black white plugs, as to my  surprise they produced different results.  See more on this difference  in my overall assessment at the end of the review.
My methodology  is to charge each mobile device on each port of the unit for 10 minutes  and measuring how much each unit was charge in that 10 minute period.  Each line in the table below represents a separate 10 minute test.
I  use Battery App by Elvison to determine how each device recognized the  charging source. 'AC' status means the charging is at full charging  rate. 'USB' status indicates charging at a lower charging rate.  'Discharging' status means that the charging rate is below the power  that the device is consuming so it slows down the discharge rate but  does not re-charge.   
I am attaching a collage with 3 photos that  to illustrate this review.   They show  the plugs on different power strips, charging different mobile devices,  as well as a close up of the plug itself.
Bolse wall charger has  re-tractable prongs which is very handy for travel. It has 4 ports: 2  universal ports, 1 Apple port, and Samsung port.  The ports are marked  on the top of the unit.  The writing is very easy to read on the white  plug, and a bit harder on the black plug.
The plug is 3 inches long and 2 inches wide. If you put the plug on the strip it takes up two slots.
The table below summarizes my findings:
✔ Nexus 7 Tablet (black plug)
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Universal port 1 -- AC ----- 4% change in charge in 10 minutes
Universal port 2 -- AC ----- 4% change in charge in 10 minutes
Apple port  ------- AC ----- 0% change in charge in 10 minutes
Samsung port  ----- AC ----- 1% change in charge in 10 minutes
✔ Nexus 7 Tablet (white plug)
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Universal port 1 -- AC ----- 3% change in charge in 10 minutes
Universal port 2 -- AC ----- 3% change in charge in 10 minutes
Apple port  ------- AC ----- 0% change in charge in 10 minutes
Samsung port  ----- AC ----- 1% change in charge in 10 minutes
✔ Samsung Galaxy Nexus Phone (black plug)
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Universal port 1 -- AC ----- 7% change in charge in 10 minutes
Universal port 2 -- AC ----- 7% change in charge in 10 minutes
Apple port  ------- AC ----- 4% change in charge in 10 minutes
Samsung port  ----- AC ----- 5% change in charge in 10 minutes
✔ Samsung Galaxy Nexus Phone (white plug)
--------------------------
Universal port 1 -- AC ----- 6% change in charge in 10 minutes
Universal port 2 -- AC ----- 6% change in charge in 10 minutes
Apple port  ------- AC ----- 3% change in charge in 10 minutes
Samsung port  ----- AC ----- 4% change in charge in 10 minutes
✔ Samsung Galaxy Tablet 7.7 (black plug)
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Universal port 1 -- AC ----- 4% change in charge in 10 minutes
Universal port 2 -- AC ----- 4% change in charge in 10 minutes
Apple port  ------- -- ----- discharging
Samsung port  ----- AC ----- 3% change in charge in 10 minutes
✔ Samsung Galaxy Tablet 7.7 (white plug)
--------------------------
Universal port 1 -- -- ----- discharging
Universal port 2 -- -- ----- discharging
Apple port  ------- -- ----- discharging
Samsung port  ----- AC ----- 3% change in charge in 10 minutes
✔ SanDisk Sansa Clip+ MP3 Player
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Universal port 1 -- worked
Universal port 2 -- worked
Apple port  ------- worked
Samsung port  ----- worked
✔ Nexus 7 Tablet & Samsung Galaxy Nexus Phone at the same time (black plug)
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Universal port 1 -- AC ----- Tablet 4% change in charge in 10 minutes
Universal port 2 -- AC ----- Phone 7% change in charge in 10 minutes
The  behaviour of both Nexus 7 Tablet and Galaxy Nexus Phone plugged in at  the same time was the same as when they were plugged in individually.
On  the black plug the Galaxy 7.7 tablet performed better on Universal  ports than on the Samsung port.  However on the white plug, the only  port that worked for Galaxy 7.7 was the Samsung port.
The MP3 player worked on all ports.
➨ Key finding:
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There  was a difference in performance between the black and the white plugs.   I can only explain it by inconsistency in the manufacturing processes.   The performance of the black plug was consistently better for all the  units.  The white plug did work, and if I did not have a black one for  comparison or did not run the same set of tests on both plugs I would  have thought the white one worked reasonably well. As an engineer I find  inconsistency in performance rather unsettling and even though the  black plug performed exceptionally well I felt I had to mark down both  plugs because potential consumers would not know whether they would be  getting an ok plug or a great plug.  The inconsistency may show up in a  plug of any color.
You can find the black charger on Amazon by following this link.
You can find the white charger on Amazon by following this link.
AshopZones review ★★★★☆