Google search educated me that the red surface is the PTFE material compatible to wider range of chemical compared to the white silicone surface.

RED PTFE/WHITE SILICONE SEPTA 13MM. RED PTFE/WHITE SILICONE SEPTA 13MM. Buy Now RED PTFE/WHITE SILICONE SEPTA 13MM. £16.38. (exc VAT). Quantity.

The PTFE/silicone small sample vials septa is an ideal choice for most HPLC PTFE/red rubber septa are popular and economical choices for general GC and ...

Sample Vial Caps&Septa, Red PTFE/white silicone septa + Blue screw cap with hole, for 2ml 9-425 screw top vial ; Septum Cleanliness, Cleanliness Test(GC Head 

We offer the best prices on Blue 9mm screw cap with white silicone/red ptfe septa , 12 x 32mm Robotic 9mm Thread Screw Top Vials and Caps.

Red PTFE/White Silicone Septa for 9mm 1.5ml HPLC Vials, Find Details and Price about Septa PTFE Silicone Septa from Red PTFE/White Silicone Septa for 9mm 

Vials, Screw Cap & Septa Only, PTFE Red/Silicone White/PTFE Red, 45° shore A, 1.0mm slit, 100/pk.

Cap, Crimp, Open Top, CLEAR 11mm with Red PTFE/ White Silicone Septa 1mm Thick PRE-SLIT. 100pcs/pk. Showing 1 to 4 of 4 entries. 10/20 ml Headspace Vials. SCION 

SSP makes autosampler septa, GC septa, bonded caps, magnetic caps, EPA/VOA ST883 BND .040” Thick, White PTFE/ Red Silicone Bonded into a 9mm Blue Ribbed ...

High purity Silicone/PTFE septum for reliable analysis results even in sophisticated analyses. Temperature restistance:-60°C up to 200°C.

Screw Thread Cap & Septa of 9-425 Screw Top Glass Vial. Red PTFE/White Silicone Septa + Red Screw Cap with Hole, for 2ml 9-425 Screw Top Glass Vial, 100/pk.

This listing is for the caps and septa only MS® HPLC and GC sample vials offer a number of benefits over the standard straight glass sample vials.

70411 - 40 durometer, white, silicone 5652 - 60 durometer, burnt orange, natural rubber. BR502 - 50 durometer, red chlorobutyl ​Clear Polypropylene · PTFE

Aluminum, clear, 5.5 mm opening, red PTFE/white silicone/red PTFE, 1.0 mm thick PTFE/Silicone Septum. Polypropylene Cap,. PTFE/Red Rubber. Septum.