CNCMANS Linear Rail 2Pcs SBR16 1500mm Linear Guide Fully Support Linear Rail Shaft Guide with 4Pcs SBR16UU Linear Bearing Sliding Block for Industrial Automation Equipment (SBR16 59.05inch)

best ones ive found easy to fix down not like the ones you can buy from vevor these are better from amazon

Really smooth running rails, extremely strong.I use these for routing large sheets of rough wood flat.The size and price is worth the time mking them into a jig over a dedicated premade set up that isn't big enough.