Check Point Security Gateways to Blade Size matrix
You can find the right Blade Size for your Security Gateway by looking ta the matix below.

Low (S) /
   DLP 500
Mid (M) /
   DLP 1500
High End (L) /
   DLP U
Ultra High End (XL) /
  DLP U
Appliances 4600 12200 12400 21400
4200 4800 Power 9070 12600
2200 IP 560 Power 5070 Power 11000
IP 280 IP 390 IP 1280 IP 2450
UTM-1 570 IP 290 IP 690
UTM-1 270 UTM-1 3070
UTM-1 130 UTM-1 2070
SG80 UTM-1 1070
Software Systems SG100 SG400 SG800 SG1200
SG200
VE801 VE1601 VE4801
IAS (Integrated Appliance Solution) *D1 *D6 *D8
*D2 *L6 *L8
*L2 *M6 *M8
*M2 *R6 *R8
*R2


Here are a few examples to help you read the matrix:
If you are looking for an IPS Blade for your 12400 Appliance, you need the IPS blade for high-end appliances.
If you are looking for an AntiVirus Blade for your SG400 Software Gateway, you need the Anti Virus Blade for mid-range gateways.
If you are looking for a URL Filtering Blade for your M8 IAS (Integrated Appliance Solution), you need the URL Filtering Blade for ultra high-end gateways.
If you are looking for a DLP Blade for your 2200 Appliance, you need the DLP 500 Blade.