The ones for softball tend to have a larger pocket than the ones for baseball to account for the difference in ball size.
You will probably want to stick with one in the 12.75" - 13" range. Anything smaller won't have a large enough pocket to be comfortable. If you consider yourself to have rather large hands, then a 13.5" or 14" would be more appropriate.
I suggest trying one in various sizes and brands to see which one(s) are the most comfortable and then shop the best price online starting here at the softballfans.com store.
X2. I use the same 1b mitt and I like it a log. It took a little time to get it properly broken in, but it is now reaching the stage where it is very g2g.
Use a Mizuno MVP. Awesome glove. There's a world of difference playing the position with a 13" outfielder glove. Use it when catching, too, to shade the plate.
Haven't seen any "softball specific" 1st base gloves yet, but would be interested to try one if I could find it locally.
I used the silverback model SB1B for 3-4 Years until it needed a bunch of TLC, last year I picked up a Worth Liberty Advanced (12") and I have been using that ever since.
I have never used a regular glove at 1st, I don't know how some of you guys do it.
RFB
RFB-RH
Renegade Series 13 inch Baseball or Softball First Base Mitt
• 13" First Base Pattern
• Conventional Back
• Single Post, Double Bar Web
Suggested List: $75.70
$59.99