Backing plate with nylon hook velcro is a designed to fail and have you buy new heads. Head gets hot due to friction (so don't press even a small amount !!) then the hooks change shape so the sanding discs don't stick and get thrown. I'll research and check the design more carefully before next purchase. Machine works fine when new head but doesn't last long. I'm on my 3rd and its getting expensive to run this machine. Unexpected.

Purchased recently and used intermittently on very small jobs for fine work,I have other sheet sanders for large work,however when working with this thing{sander] the other day it just stopped working,I picked it up to start and no go,very unhappy with this as it was not cheap and has only lasted a short time on very light work,absolutely useless thing,thought Bosch was better than what I have paid for.

Wish I'd read these reviews before I bought mine...
-Dust collection box is hard to remove and clean and sometimes pops off while you are sanding. ..and the o ring broke so I had to order another.
-The biggest problem is that it's been throwing discs since I bought it and now they don't adhere at all - this seems to be a common issue
-I'm ordering another backing plate now and will see whether this fixes it.
-If not then I will provide another update here and will never buy another Bosch power tool again. This one has major design flaws. Just goes to show that paying a premium doesn't automatically get you quality.

Purchased this sander for maintenance and repair work on hire products in my business. I needed something reliable and gutsy enough to get decent sized jobs done in good time. This sander has plenty of power and has a very clever anti-vibration system so the user doesn’t suffer the old pins and needles that some other ROS present. Totally recommended.

I bought a new Ryobi sander specifically for this large job i had to do - sanding 5 light years of cornice glue off an entire ceiling off a sprawling house that we were going to put another ceiling straight over top of. Anyway the Ryobi died after a couples of hours so I drove straight to Bunnings and replaced it with the Bosch. OMG unbelievable difference, the Bosch ripped through the old cornice glue like it was made from meringue cake base. The discs do come off every now and then which is a bit annoying, but weirdly for me they were coming off when the sanding discs were ready to change. The filter seems to work well but the design is crap for getting it on and off (hence the 4 stars)
I would buy another in a heartbeat

This is a decent little sander. Not high end, but not a high end price so that's ok. As a working sander, it really does that. It works. I have almost no issue with it. Solid performer. Highly recommend, provided one thing... You better not be too worried about how the dust catching system functions. Because basically it doesn't. The thing falls off with the slightest bump, but it's ok because it pretty much never caught the dust.

I'm still fine with it - i just use it outside and use a mask. Something I do for most work, so no issue for me. So I still rate it a 4 star for price etc - just know what you are buying.

Had one of these for a short time, the thing started to vibrate, i couldnt work out what the problem was, turned out the single bolt that holds the sanding pad onto the sander had worked itself loose and as the surround of the base pad is plastic and the cog it attaches to is metal the metal destroyed the pad fitting rendering it useless. This was just out of warranty and Bosch were not interested in helping out in any way. Even though this is a design fault and not a wear and tear issue.The replacement pads are around $45 not cheap if the sander keeps destroying them.
No more Bosch fo me thanks.

after a couple of times using this model the speed controller failed and the machine would not run lower than half speed, then it failed altogether, replacement part is $44 from https://www.toolspareparts.com.au/bosch-pex-300-ae-3603ca3040-spare-parts.html I should have returned at the first instance of failure but you know what its like just wanting to get the job done and move onto other bits so did not follow up on warranty, wish I had, also the dust catcher is pretty much useless, now replaced with Ryobi, so far so good.

Go to Bosch Australia try to get spare parts cant order through them what a joke think may have to use different manufacturer didn't mind the tools but if you cant get help from them what's the point cant order through dealer as the cost of replacing the sanding pads all the time gets to dear with dealer mark up and takes to long to get part in.

the sander works OK but the dust catcher is useless, dust clouds are the order of the day. Even when I cleaned the filter and took care to refit it to the machine, it still emits dust from around the lid. Checked that its fitting Ok but no change. Disappointing dust catcher.

Light and perfectly weighted orbital sander. I would say the best I have used. Variable speed control works well. Great control with the front auxiliary handle. Low noise. And comes in a case. Cannot fault!

Bosch GEX 125 AC Professional is in the top two sanders i have ever used. The one that i like more is the Festool 57187, because of the higher stability it offers. Got the Bosch GEX 125 sander as an recommendation from BestRandomOrbitSanders website and I am really thankful to these guys!

I am just a DIYer, I knew an orbital sander would help me get a better finish on my projects, but can't really fork out for sanders at the top of the market. I have been really impressed with this unit, the adjustable power output is a nice feature and the dust collection does an ok job, better than my 1/3 sheet makita anyway.

I should say that I didn't get much help from Bunnings Brendale while selecting this, the staff member in the tool shop didn't seem to know too much about the sanders in their lineup. Tho i have also got great helpful service there when buying a drill, guess it's just hit and miss.

Not a bad sander, onto my 3rd base pad as the Velcro wears very quickly, major problem, call center not very helpful,the other problem is with this review, I only needed 22 words but I couldn't post it until I had written 50, also very frustrating, regards Craig, good bye

As others have found these Bosch 400 sanders throw the sanding discs. Very poor velcro attachment plate used on backing pad. Not fit for purpose IMHO. I've already replaced it twice with the Bosch OEM backing pads, no better, they go bad soon after. Bosch OZ know about this problem yet have not offered to replace these defective parts nor owned up to the issue. Very poor IMHO. Web searches reveal this is a common issue.
Their response is to tell readers to call their helpline where you will be told crap by someone who knows nothing and offered nothing useful as a remedy. I will not be buying another Bosch orbital sander not will I recommend them.

Brought two to renovate the inside of the house. Both throw pads now after working for approx 12 hours. Do not buy useless. The basic function of a sander is to sand this doesn't do that one the pad loses ability to hold pads. Would not buy this type of sander again