DetailsInfill strips, or fillets, are used to between wooden spindles to set the spacing width between them and fill in the gaps. Size 55mm. Infill Strips are supplied at 895mm long. To be cut into fillets on site. Image shown of similar product. You need one length of 895mm infill strip for every 4 spindles. (This piece allows for both the handrail and the baserail slots to be filled).