The magnetic piece is great for holding the roller in place.
But First star is not too cold of a color that I may try to live with it and see if I grow to like it once I get my renos completed. I was trying for a warmer gray with brown undertone, so in that regards, I may still repaint. Lengthy post, I know :) In the end, I do like the color. I'm sure if I had halogen pot lights it may bring out undertones more or less than compare to soft white pot lights. I think it's warm light or soft white color. I should let you know, I have LED pot lights. In some areas have a bit of blue undertone in other areas looks more like a true gray, just 1 or 2 shades darker. For example, I get a lot of light during the day and the walls look like very light true gray, but in the evening things change. It does have a tiny bit of a blue undertone under different lighting or times during the day. We'll, I got the correct color up on the walls. When I started to paint my walls, I started with the mistint can. I went to SW and showed the manager, she agreed it was a mistint and gave me a new can of first star. I took a dab of paint and put it on the paint chip, there was an obvious difference. But mechanically, it ain't happening in their Extra White base. I can't say definitively, because I've not seen it attempted. It's possible SW could match Simply White in their High Reflective White base. which of course, would make the color darker. You can't make a white base any whiter, and you can't overcome a yellow-green tinge except by adding a certain amount of pigment. Yet Ben Moore's Simply White color is only at 106.6 degrees (Yellow family) with a lightness of 95.6. Extra White is at 113 degrees on the Lch color wheel (Green-Yellow hue family), with a lightness of 94.4. The SW version comes out looking more yellow-green than the Ben Moore color - no big surprise here because of the SW Extra White base. I've had to go on several calls because of it. In particular, I have never seen SW match Simply White. Thus, if you are trying to reproduce a very light color, you have that to contend with. They will struggle with many of the lighter colors, whites and near-whites, because the SW base is already darker than Ben Moore's BEFORE any tint is added.
But I will add my 2c about SW matches of Ben Moore colors. As always, I defer to Lori Sawaya in all things color.