I take it that the mat the OP is referring to, is the stock SL1200/1210 Technics mat.
A very useful item, good quality and often available for peanuts as they are discarded from the box by the DJ users.
Not only do I use one on a SL1210, one is a good fit on a Fons CQ30.
I have recently re joined the Garrard 401 owners after a lapse of 40 years! The original Garrard mat had become very hard and luckily I had been given an unused Technics mat, with just a felt disc to infill the centre recess in the Garrard platter, the Technics proved a perfect fit.
Works for me.