Here's that description from EBay again:

A simple switchable Kernal ROM adaptor which accepts programmed 2532 and 27xxx Eproms.

The larger the Eprom the more Kernals you can have. Using the 10 position DIL switch you can select the Eprom type and which bank to use, allowing you to have a multitude of different Kernals all on the same ROM. For Example Standard Commodore Kernal, Jiffy DOS, Dolphin DOS, Quick DOS and many more.

Instructions from Dela included (in German)

Shareware Plus's blog states, simply:

We're excited about this, its a remake of the DELA 87010, a low cost, multi-kernal ROM Adapter for the Commodore 64. A great, simple solution to equipping your 64 with lots of different Kernals, all available at a flick of a switch!

The handy ROM selector by DELA, the 87010 is now available and includes instructions!

And, from the translated documentation, we get this description:

The DELA programming adapter allows you to program the 27256 type EPROMs with an eprom program that can program 27128 type EPROMs.

Additionally you can use the programming adapter with 2532 EPROMs and the Commodore ROMs.

The programming voltage can be lowered to 12.5V, so you can burn all 12.5V types of the 27xxx series.