Over the last couple of years, I've placed several orders from MP. Generally, I've found the corner connectors and the t- connectors to be satisfactory, although the application to 1/2" conduit is sometimes a little challenging. But, they work.
The 135 degree connector is another story, and, simply doesn't seem to meet the same standards. Furthermore, trying to deal with the issues with customer service has failed utterly, usually with an initial response followed by profound "radio silence".
My goal in choosing the 135 degree connectors was to use two in a row with three pieces of conduit to form a panel that would result in a 90 degree transition but be more gradual. (See the photo) This was to form a roof on an enclosure.
However, the plan failed.
First, in 4 of the 135 degree connectors, NONE of the nut-traps worked. The nuts simply spin. So, imagine the challenge of trying to hold 3 pieces of conduit together, one of which is 40" long while having to not only tighten the bolt, but also grab the nut with a 10mm socket or wrench. Ya...sure...youbetcha.
The major problem however, is that the 135 degree connectors are not 135 degrees! This means that when you use two of them, you don't get a 90 degree effect, but only about 85 degrees. Thus, the claim that you can form an octagon is not true (unless you bend the conduit to bring the last two pieces together.)
I had no choice but to abandon my design.
To make matters worse, my attempts to reach "customer service" also failed. I reached out to describe the problem from the "Contact Us" page, describing the problem. While I received an initial response, it was clear that the responder, Dave, didn't read my comment carefully and so didn't understand the issue. So, in order to clarify, I followed up with two emails, including photos of the problem.
These were met with no response.
So, I sent another inquiry through the "Contact" page, and again got a response, this time proposing to arrange a phone call. I confirmed that this would be possible, but requested that they review the entire set of information that I provided to avoid wasting time. Radio silence.
So, I tried one last time by email, this time cc'ing the owner, Dave, and received a response, again requesting when a good time for a call would be. This was 3 business days ago, and I have gotten neither a response to that email or a phone call.
At this point, the issue is probably moot, so I have proceeded with my alternative design, using fewer MP parts.
Final comment: I realize that MP is a small company and the staff has many demands on their time. I also suspect that the 135 connector has a manufacturing defect, which can happen. The major problem here is that they have had such a poor communication response, in addition to providing defective parts. At this point, I will be very reluctant to do business with them, except for the extremely "tried and true" commodity parts.