Taglerocktech,   Sorry to hear you had such issues getting your inquiry correctly answered, but to let you know now the S5148 does come with two rails, as you can see from page 8 here.    Hope this helps answer your question, let me know if you have any other.     
Hello Everyone,   I'm trying to figure out what comes in the box with a Dell S5248F-ON, in particular I'm trying to figure out if it comes with rack mounting hardware.  I've been through spec sheets, called dell, called dell distributors, and searched youtube for unboxing and review videos and I haven't been able to find an answer.  I've also tried configuring the switch and seeing if the mounting hardware is a configurable option but it isn't, and there is nothing that says it comes mounting hardware either.  So I'm hoping someone on here can give me a definitive answer of whether or not it comes with rack hardware, or if you have to order it separately, and if you do have to order it separately, whats the part number. 
S5248F-ON Box Contents