This is a complete kit of TR-505 ROM expansion kit originally designed by HKA.

hkadesign.org.uk/tr505expansion.html 

It comes with all required components including preprogrammed EPROM. You'll need to solder all parts together, as well as desolder the original EPROM. You'll find the instruction at HKA site to perform those steps. You may decide to use male/female headers if you need to have it detachable, but then you may find lack of space internally to close the case completely. Make sure you have skills and capabilities to do that. This is not for beginners, let do the job professional if in doubts. For obvious reasons, no returns accepted.

Please, note, I'm not affiliated with HKA Design. I produced these boards myself to be used in my projects and have enough leftovers to sell outside. As of November'20 HKA design has removed all original design files and PCB layouts from their website that previously were available to others. They are not responsible for third party builds and no longer provide the support for them. If you buy it here, you should contact me for all support inquiries.