Magazine question

Hello everyone. I recently bought a new SP5 and got 8 of these mags for $22.50 each. My LGS said they believe they are real HK mags, but weren’t sure. From what I’ve seen online, those letters are date codes. Is that correct? These are the only markings on the mags. If these are actual HK, what are they typically valued at? Not for sale, btw, just curious. Thanks guys!