This may sound like blasphemy, but I bought a stamped sheet metal filter socket at Wal-Mart (the same socket fits VW spin-on filters) and I prefer it to my MB filter socket. The MB socket is a nice, cast aluminum item, beautifully made. BUT, both sockets become firmly attached to the filter (or filter cap in the case of the M104) when removing at filter or filter cap. To remove the socket from the filter with the Wal-Mart tool, I simply tap the side of the socket. With the MB tool I have to drive a rod through the hole in the center of the tool. This sometimes takes quite a bit of force before it drives out the filter and with the plastic filter caps for the M104 I'm afraid one could damage the cap. I always buy the best tools I can find, but in my opinion, this is a case where the "cheapie" is the best tool.