I got the BodySolid 6ft Black Bar myself. I have no complaints and it was under $100.
The grooves are meant to provide more friction for the plates. I have a bar with grooves in the sleeves as well.
The bar you wanted identified, may or may not be this one. The hex bolt holding the sleeve on is poor design. If the bolt comes loose, you will have a bad day.
Are you attending a gym, or working out at home? At my gym they have 15, 20, 35 & 45lb bars. I used the 15lb bars for a long time on a lot of exercises until I was ready to move up. Ask around at the gym to see if they have different sizes :)
edit: At my gym the 15lb bars are silver pic
The 20lb bars are curved (actually looks like they are called "curl bars") pic
The 35lb bars are black (sometimes called "womens" bar) pic
The 45lb bars are black but slightly longer and a tad wider than the 35lb pic
Body Solid Oly Power Bar 6 ft Black https://www.amazon.com/dp/B003TPRM2C/ref=cm_sw_r_other_awd_qadlwbRGGZ8CQ