These are all currently (27.07.2016) available labels for your Seiko label printer.

Product Code	Description	Dimension
SLP-1BLB	Paper Label, Blue, Permanently Adhesive	28mm x 89mm
SLP-1GLB	Paper Label, Green, Permanently Adhesive	28mm x 89mm
SLP-1OLB	Paper Label, Orange, Permanently Adhesive	28mm x 89mm
SLP-1PLB	Paper Label, Pink, Permanently Adhesive	28mm x 89mm
SLP-1RLB	Paper Label, White, Permanently Adhesive	28mm x 89mm
SLP-1RLC	Plastic Label, Transparent, Permanently Adhesive	28mm x 89mm
SLP-1YLB	Paper Label, Yellow, Permanently Adhesive	28mm x 89mm
SLP-27210	Paper Label, White, Permanently Adhesive	10mm x 71mm
SLP-2RL	Paper Label, White, Permanently Adhesive	28mm x 89mm
SLP-2RLC	Plastic Label, Transparent, Permanently Adhesive	28mm x 89mm
SLP-2RLE	Paper Label, White, Permanently Adhesive	36mm x 89mm
SLP-2RLH	Paper Label, White, Permanently Adhesive	28mm x 89mm
SLP-35L	Paper Label, White, Permanently Adhesive	11mm x 38mm
SLP-4AST	Paper Labels, Color Assorted, Permanently Adhesive	28mm x 89mm
SLP-DIA	Paper Voucher, White, Non-adhesive	57mm x 150mm
SLP-DRL	Paper Label, White, Permanently Adhesive	54mm x 70mm
SLP-ENT	Paper Label, White, Non-adhesive	39mm x 75mm
SLP-ENTL	Paper Tag, White, Non-adhesive	57mm x 89mm
SLP-FCS2	Paper Label, White, Non-adhesive	57mm x 89mm
SLP-FLW	Paper Label, White, Permanently Adhesive	14mm x 87mm
SLP-FN	File Folder Label Narrow, White, Permanently Adhesiv	38mm x 190mm
SLP-FW	File Folder Label Wide, White, Permanently Adhesive	54mm x 190mm
SLP-JWL	Plastic Label, White, Permanently Adhesive	11mm x 51,5mm
SLP-MPL4	Plastic Label, White, Permanetly Adhesive	54mm x 101mm
SLP-MRL	Paper Label, White, Permanently Adhesive	28mm x 51mm
SLP-MRLB	Paper Label, White, Permanently Adhesive	28mm x 51mm
SLP-MRLC	Plastic Label, Transparent, Permanently Adhesive	28mm x 51mm
SLP-NB	Paper Label, White, Permanently Adhesive	54mm x 70mm
SLP-NR	Paper Label, White, Permanently Adhesive	54mm x 70mm
SLP-OPMRL	Paper Label, White, Permanently Adhesive	28mm x 51mm
SLP-OPSRL	Paper Label, White, Permanently Adhesive	54mm x 101mm
SLP-R2RL	Paper Label, White, Removable	28mm x 89mm
SLP-RDO	Paper Label, Orange, Permanently Adhesive	ø54mm
SLP-RMRL	Plastic Label, White, Removable	28mm x 51mm
SLP-RND	Paper Label, White, Permanently Adhesive	ø 28mm
SLP-RSRL	Paperetikett, White, Removable	54mm x 101mm
SLP-RTL	Paper Label, White, Partially Adhesive	37mm x 37mm
SLP-RTNC	Plastic Label, Transparent, Permanently Adhesive	16mm x 51mm
SLP-SRL	Paper Label, White, Permanently Adhesive	54mm x 101mm
SLP-SRLB	Paper Label, White, Permanently Adhesive	54mm x 101mm
SLP-SRLC	Plastic Label, Transparent, Permanently Adhesive	54mm x 101mm
SLP-STAMP1	Online Stamp Label, White, Permanently Adhesive	36mm x 42mm
SLP-STAMP2	Online Stamp Label, White, Permanently Adhesive	36mm x 67mm
SLP-TMRL	Plastic Label, White, Permanently Adhesive	28mm x 51mm
SLP-TP	Paper Label, White, Permanently Adhesive	25mm x 54mm
SLP-TRL	Plactic Label, White, Permanently Adhesive	28mm x 89mm
SLP-VSL	Paper Label, White, Permanently Adhesive	19mm x 147mm
SLP-VTL	Paper Label, White, Permanently Adhesive	46mm x 78mm
SLP-ZIP	Paper Label, White, Permanently Adhesive	51mm x 59,5mm

There is a the list with all distributors if you want to buy one of those labels