The 20A has been used in the bulk of the Estes kits offered in the BT-20 tube size. The Ninja, Wizard, Zinger, Viking and Hi-Flier are just some of the kits that can be built using this cone. The 20Y is less versatile from a cloning standpoint, having only been used in the Yankee, but it would likely translate well to many of your own designs.

These noise cones are quite comparable to the name brands, but without the hefty price tag. I love these selections, as my go to alternative.

As pictured, you'll be getting 4 BT-20 Estes nose cones. These are the nose cones used in the Viking/Wizard and Yankee BT-20 sized rockets (the Yankee has been discontinued by Estes as of the time of this writing). It appears this 4-pack with 2 types of nose cones has the Estes product number of 303161. But if you go to Estes.com, they don't recognize this product number. Instead, they recognize product number 003161. This is also a 4-pack of BT-20 nose cones, but comes 4 different types, not 2. One is the conical one used in the Yankee, one is the elongated o-give style used in the Wizard/Viking, one is an elongated parabolic shape (this might not be the correct technical term, but bear with me) and the last one is a domed parabolic shape (probably not the correct technical term of the shape, sorry) that's similar to the shape of the Big Bertha nose cone. I think the elongated parabolic shaped nose cone is used in the LEO Space Train Estes kit. As for the quality of the nose cones, they're good and on par with what you'd see in the Estes model rocket kits that use these respective nose cones. I have noticed some imperfections in terms of the bottom part of the nose cones, just above shoulder. These aren't a problem and are easily remedied with some targeted sanding, but it's something to be aware of. Also, not all nose cones have this blemish, as I've build several Yankee, Viking and Wizard Estes kits (as well as purchased several of these BT-20 4-packs) and most of them didn't have these flaws.