It says SofTan'd with a bull.
I believe it's a slightly softer version of the pure old school horween lining. not as soft as deer tanned.
the reason i say this is because i had the priviledge of breaking in a similar pro T with the SofTan'd lining and it took forever (in 1984). i think it was Rawlings' 1st attempt at making the glove a little (2%?) easier than full Horween lined gloves.
28years later i'm still using this glove and it's in excellent shape
http://www.vintagebaseballgloveforum.co ... 46&start=0