The Brause 361 nib (aka "the blue pumpkin") is a medium type of nib -- some flex but not a lot and can be used with a lot of pressure to get dynamic contrast or used with a lighter hand and obtain less contrast and fine hairlines.
I think this nib is cool looking and I love the blue color. This nib uses the standard Speedball B holder.
I use this nib when a project calls for larger size lettering as this nib can maintain the integrity of the letters.
I like using this nib for envelopes when I am using a lettering style that calls for large lettering. This nib can hold a lot of ink before it needs to be reloaded. Be sure to take off any excess ink when reloading because you will get pooling of ink (which of course I was not able to replicate when I tried
I also like using this nib for print-style lettering -- I think the thick & thins look nice.
Have fun experimenting with this nib!