Pentair 070428Z T-Bolt Replacement Pool/Spa Stainless Steel Pool/Spa D.E. Filter T-bolt replacement Fits Pentair SM & SMBW 2000 Series pool and spa stainless steel pool and spa D.E. filters Also fits Pentair Nautilus plus pool and spa stainless steel pool and spa D.E. filter Measures 1/4-20 by 3-1/2